anatomy and histology of the skin. skin – the more large organ in the body surface – 1.5-1.8...

Anatomy and histology of the skin Anatomy and histology of the skin

Skin – the more large organ in the bodySkin – the more large organ in the body surfacesurface – 1.5-1.8 sqm; – 1.5-1.8 sqm; thicknessthickness::

0.2-0.5 mm (eyelid, prepuce);0.2-0.5 mm (eyelid, prepuce); 3-5 mm (palms and soles).3-5 mm (palms and soles).

weightweight:: 4-5 kg;4-5 kg; 20 kg with hypodermis.20 kg with hypodermis.

glabrous skinglabrous skin – palms and soles; – palms and soles; hair bearing skinhair bearing skin..

Organization of the human skinOrganization of the human skin:: the skin is composed of the skin is composed of four distinct layersfour distinct layers::

the the epidermisepidermis;; the the dermo-epidermal junctiondermo-epidermal junction;; the the dermisdermis;; the the hypodermishypodermis..

Histology of the epidermisHistology of the epidermis

stratum germinativum (Basal cell layer);stratum germinativum (Basal cell layer); stratum spinosum (Squamous cell layer); viable epidermis;stratum spinosum (Squamous cell layer); viable epidermis; stratum granulosum (Granular cell layer);stratum granulosum (Granular cell layer); stratum lucidum;stratum lucidum; stratum corneum (Horny layer) – nonviable epidermis.stratum corneum (Horny layer) – nonviable epidermis.

KeratinocytesKeratinocytes

Dendritic cellsDendritic cells

Basal Cell LayerBasal Cell Layer

a single range of columnar cells, with basophilic a single range of columnar cells, with basophilic

cytoplasm, dark-staining oval or elongated nucleus, many cytoplasm, dark-staining oval or elongated nucleus, many

ribosomes, tonofibrils (keratin filaments) into fine bundles, ribosomes, tonofibrils (keratin filaments) into fine bundles,

melanin granules (transferred from melanocytes);melanin granules (transferred from melanocytes);

the cells are connected with each other by desmosomes the cells are connected with each other by desmosomes

(symmetrical, laminated structures) and with basement (symmetrical, laminated structures) and with basement

membrane by hemidesmosomes.membrane by hemidesmosomes.

Basal cell layer (glutaraldehide- osmium Basal cell layer (glutaraldehide- osmium fixation)fixation)

Squamous Cell LayerSquamous Cell Layer

5-20 ranges of polygonal cells with long axis parallel to the 5-20 ranges of polygonal cells with long axis parallel to the skin surface, eosinophilic cytoplasm, clear rounded skin surface, eosinophilic cytoplasm, clear rounded nucleus, large bundles of keratin filaments, attached to nucleus, large bundles of keratin filaments, attached to desmosomes;desmosomes;

the new organelles in the upper spinous cells the new organelles in the upper spinous cells → lamellar → lamellar granules (keratinosomes, Odland bodies) – they contain granules (keratinosomes, Odland bodies) – they contain polysaccharides, free sterols, lipids, hydrolytic enzymes; polysaccharides, free sterols, lipids, hydrolytic enzymes; their contents are discharged into the intercellular space at their contents are discharged into the intercellular space at interface with granular layer.interface with granular layer.

Squamous cell layerSquamous cell layer

Granular Cell LayerGranular Cell Layer

3-10 ranges of diamond-shaped or flattened cells, with 3-10 ranges of diamond-shaped or flattened cells, with horizontal long axis, cytoplasm filled with basophilic horizontal long axis, cytoplasm filled with basophilic kertohyaline granules (irregular in size and shape, with kertohyaline granules (irregular in size and shape, with particulate substructure);particulate substructure);

the dissolution of the nucleus and cell organelles is the dissolution of the nucleus and cell organelles is initiated; keratin filaments in large bundles;initiated; keratin filaments in large bundles;

keratinosomes migrate towards the periphery of the cells keratinosomes migrate towards the periphery of the cells and discharge their lipid components.and discharge their lipid components.

Horny LayerHorny Layer

4-10 ranges of eosinophilic, flattened cells, arranged in 4-10 ranges of eosinophilic, flattened cells, arranged in vertical stacks, that have lost nuclei and cytoplasmic vertical stacks, that have lost nuclei and cytoplasmic organelles;organelles;

keratin filaments are aggregated in macrofibres under the keratin filaments are aggregated in macrofibres under the influence of filaggrin;influence of filaggrin;

highly insoluble cornified envelope within the plasma highly insoluble cornified envelope within the plasma membrane, that contain involucrin, loricrin, keratolinin;membrane, that contain involucrin, loricrin, keratolinin;

the loss of desmosomes.the loss of desmosomes.

Stratum lucidumStratum lucidum

an additional homogenous eosinophilic zone between an additional homogenous eosinophilic zone between granullar cell layer and horny layer, in palmo-plantar skin;granullar cell layer and horny layer, in palmo-plantar skin;

contains cells with dense cytoplasm, opaque membranes, contains cells with dense cytoplasm, opaque membranes, degenerated nucleus, without organelles;degenerated nucleus, without organelles;

keratin filaments are immersed in a matrix of eleidine.keratin filaments are immersed in a matrix of eleidine.

Acral skin – layers of the epidermis: basal (green), squamous (black), granulous (red), lucidum (blue), horny (yellow). Blood vessels (arrows from dermis).

Normal skinNormal skin

Acral skinAcral skin

EpidermEpidermisis

Melanocyte

Dermis

Melanin granules

Langerhans Cells

Keratinocyte

Dendritic Cells of the Epidermis - MelanocytesDendritic Cells of the Epidermis - Melanocytes

dendritic cells localized between the basal cells;dendritic cells localized between the basal cells;

inin section stained with hematoxylin-eosin-clear cells, with section stained with hematoxylin-eosin-clear cells, with

small, dark-staining nucleus, clear cytoplasm;small, dark-staining nucleus, clear cytoplasm;

the dendritic processes recognized with dopa reaction, the dendritic processes recognized with dopa reaction,

staining with silver nitrate;staining with silver nitrate;

in electron microscopy differ from keratinocytes by lack of in electron microscopy differ from keratinocytes by lack of

tonofilaments or desmosomes;tonofilaments or desmosomes;

melanocytes contain melanosomes, specialized organelles melanocytes contain melanosomes, specialized organelles

that synthesize melanin, that is transferred to that synthesize melanin, that is transferred to

keratinocytes (apocopation);keratinocytes (apocopation);

the evolution of melanosomes in 4 stages: round, ellipsoid, the evolution of melanosomes in 4 stages: round, ellipsoid,

partially melanized, completely melanized.partially melanized, completely melanized.

MelanocyteMelanocyte

Langerhans CellsLangerhans Cells

dendritic cells of mesenchimal origin, localized in dendritic cells of mesenchimal origin, localized in suprabasal epidermis, dopa negative;suprabasal epidermis, dopa negative;

in sections stained with hematoxylin-eosin-clear cells;in sections stained with hematoxylin-eosin-clear cells;

histochemical stains (adenosine phosphatase, histochemical stains (adenosine phosphatase, aminopeptidase) – for identifying and differentiating from aminopeptidase) – for identifying and differentiating from melanocytes alfa D manositase; staining with gold melanocytes alfa D manositase; staining with gold chloride;chloride;

demonstrated with monoclonal antibody OKT6; by demonstrated with monoclonal antibody OKT6; by immunoperoxidase technique or immunofluorescence;immunoperoxidase technique or immunofluorescence;

Langerhans CellLangerhans Cell

Langerhans CellsLangerhans Cells

in electron microscopy – relatively clear cytoplasm, in electron microscopy – relatively clear cytoplasm, lobulated nucleus, well developed endoplasmic reticulum, lobulated nucleus, well developed endoplasmic reticulum, Golgi complex and lysososmes; lack of tonofilaments and Golgi complex and lysososmes; lack of tonofilaments and desmosomes, presence of Bierbeck granules; recognized desmosomes, presence of Bierbeck granules; recognized by monoclonal antibody anti-Lag (Langerhans-associated by monoclonal antibody anti-Lag (Langerhans-associated granule);granule);

Langerhans cells express on their surface HLA-DR, DP Langerhans cells express on their surface HLA-DR, DP and DQ antigens, T6 antigen CD1 (CD1a, CD1c), CD4 and DQ antigens, T6 antigen CD1 (CD1a, CD1c), CD4 (HIV receptor), CD14, CD33, VLA (very late antigen), (HIV receptor), CD14, CD33, VLA (very late antigen), adhesion molecules et al. and have receptors for Fc (Fcadhesion molecules et al. and have receptors for Fc (Fcγγ and Fcand Fcεε) of IgG and IgE and C3b, C4d, CD23 (IgE ) of IgG and IgE and C3b, C4d, CD23 (IgE receptor in atopic dermatitis), DEC 205 multilectine etc. A receptor in atopic dermatitis), DEC 205 multilectine etc. A new identified lectine (Langerin) is a endocitic receptor.new identified lectine (Langerin) is a endocitic receptor.

Merkel CellsMerkel Cells

dendritic cells localised between the basal cells, directly dendritic cells localised between the basal cells, directly above the basement membrane;above the basement membrane;

in light microscopy can be recognized in silver in light microscopy can be recognized in silver impregnated sections;impregnated sections;

in electron microscopy – lobulated nucleus, clear in electron microscopy – lobulated nucleus, clear cytoplasm, electron-dense granules, strands of filaments, cytoplasm, electron-dense granules, strands of filaments, occasional desmosomes; unmyelinated nerve endings are occasional desmosomes; unmyelinated nerve endings are associated with Merkel cells.associated with Merkel cells.

Indeterminate CellsIndeterminate Cells

have ultrastructural features of Langerhans cells but lack have ultrastructural features of Langerhans cells but lack Birbeck granule;Birbeck granule;

react specifically with the monoclonal antibody OKT6.react specifically with the monoclonal antibody OKT6.

Histology of the dermo-epidermal junctionHistology of the dermo-epidermal junction the the indeterminate filamentsindeterminate filaments of basal keratinocytes; of basal keratinocytes;

the the basal plasma membranebasal plasma membrane of keratinocytes, melanocytes and Merkel of keratinocytes, melanocytes and Merkel cells;cells;

hemidesmosomeshemidesmosomes: focal thickenings of the basal plasma membrane of : focal thickenings of the basal plasma membrane of keratinocytes, with an intercellular component (the attachement plaque) keratinocytes, with an intercellular component (the attachement plaque) and an extracellular component (sub-basal dense plate);and an extracellular component (sub-basal dense plate);

the the basement membranebasement membrane with 3 layers: with 3 layers: lamina lucidalamina lucida, , lamina densalamina densa and and lamina fibroreticularislamina fibroreticularis;;

anchoring filamentsanchoring filaments: very fine, vertically orientated structures that connect : very fine, vertically orientated structures that connect hemidesmosomes at lamina densa;hemidesmosomes at lamina densa;

anchoring fibrilsanchoring fibrils: short curved structures that insert into the lamina densa : short curved structures that insert into the lamina densa and extend into the dermis and insert into anchoring plaques or curve back and extend into the dermis and insert into anchoring plaques or curve back in lamina densa;in lamina densa;

anchoring plaquesanchoring plaques: amorphous bodies in the superficial dermis;: amorphous bodies in the superficial dermis;

the the elastic microfibrilselastic microfibrils, that extends into the dermis and may enmesh with , that extends into the dermis and may enmesh with dermal elastic fibres.dermal elastic fibres.

Histology of the dermisHistology of the dermis

Layers of the dermisLayers of the dermis:: papillary dermis (the uppermost part);papillary dermis (the uppermost part); reticular dermis (subpapillary layer).reticular dermis (subpapillary layer).

Components of the dermisComponents of the dermis:: cells;cells; fibres;fibres; ground substance.ground substance.

Cells of the dermis:Cells of the dermis:

fibroblastfibroblast - a cell at an early stage of differentiation; - a cell at an early stage of differentiation; fibrocytefibrocyte – a cell fully differentiated; – a cell fully differentiated; mesenchymal origin;mesenchymal origin;

small and spindle shaped (S-cell) or larger, flatter, small and spindle shaped (S-cell) or larger, flatter, amoeboid (A-cell);amoeboid (A-cell);

produce collagen and elastine.produce collagen and elastine.


mast cellmast cell: originate from haematopoietic bone marrow: originate from haematopoietic bone marrow ovoid or spindle shape, mono or binuclear, with round ovoid or spindle shape, mono or binuclear, with round

acidophilic cytoplasmic granules, which stain acidophilic cytoplasmic granules, which stain metachromatically with toluidine blue or Giemsa;metachromatically with toluidine blue or Giemsa;

localized around blood vessels, nerves and localized around blood vessels, nerves and appendages, in subpapillary dermis;appendages, in subpapillary dermis;


macrophagemacrophage: originate from bone marrow, is larger than : originate from bone marrow, is larger than

monocyte, with clear cytoplasm, lighty staining elongated monocyte, with clear cytoplasm, lighty staining elongated

nucleus, well developed rough endoplasmic reticulum and nucleus, well developed rough endoplasmic reticulum and

Golgi apparatus, intermediate filaments;Golgi apparatus, intermediate filaments;

is a is a general scavengergeneral scavenger implicated in the ingestion and implicated in the ingestion and

killing of micro-organisms and the degradation of killing of micro-organisms and the degradation of

foreign substances;foreign substances;

secrete several enzymes;secrete several enzymes;

possess numerous receptors.possess numerous receptors.

Fibers of the dermis:Fibers of the dermis:

collagen fiberscollagen fibers:: in light microscopy: bands with faint longitudinal in light microscopy: bands with faint longitudinal

striations; in dark field, each fiber is a bundle of parallel striations; in dark field, each fiber is a bundle of parallel fibrils;fibrils;

in E.M.: fibrils with cross striations;in E.M.: fibrils with cross striations; structure of collagen: 3 polypeptide chains, coiled in a structure of collagen: 3 polypeptide chains, coiled in a

triple helix (helical domain) and a globular domain at triple helix (helical domain) and a globular domain at each end (amino-N-terminal domain and carboxy-each end (amino-N-terminal domain and carboxy-terminal domain).terminal domain).

reticulin fibersreticulin fibers:: a special type of thin collagen fibers;a special type of thin collagen fibers; in light microscopy, with silver nitrate stains black;in light microscopy, with silver nitrate stains black; in E.M.: fibrils separated by an interfibrilar substance.in E.M.: fibrils separated by an interfibrilar substance.

Fibers of the dermis:Fibers of the dermis:

elastic fiberselastic fibers::

in light microscopy, with orcein or resorcin-fuchsin, thin in light microscopy, with orcein or resorcin-fuchsin, thin bundles, that in the papillary dermis form an bundles, that in the papillary dermis form an intermediate plexus of elaunin fibers running parallel to intermediate plexus of elaunin fibers running parallel to the dermal-epidermal junction; oxytalan fibers, the dermal-epidermal junction; oxytalan fibers, perpendicular to the dermal-epidermal junction;perpendicular to the dermal-epidermal junction;

Ground substanceGround substance

an amorphous substance: contains proteoglycans, an amorphous substance: contains proteoglycans, glycosaminoglycans, electrolytes, water;glycosaminoglycans, electrolytes, water; the staining methods of the ground substance:the staining methods of the ground substance:

the production of metachromasia;the production of metachromasia; colloidal iron;colloidal iron; Alcian blue, ruthenium red;Alcian blue, ruthenium red;

in electron microscopy: flocculent and filamentous in electron microscopy: flocculent and filamentous material.material.

Histology of the hypodermisHistology of the hypodermis

adipocytesadipocytes, organized into lobules defined by septa of , organized into lobules defined by septa of

fibrous connective tissue with blood vessels and nerves.fibrous connective tissue with blood vessels and nerves.

Skin and its appendagesSkin and its appendages

Histology of the skin appendagesHistology of the skin appendagesEccrine sweat glandEccrine sweat gland 2-4 million, distributed over nearly entire body surface; most 2-4 million, distributed over nearly entire body surface; most

numerous on the palms, soles and in the axillae;numerous on the palms, soles and in the axillae; two segments:two segments:

the secretory coil; the duct.the secretory coil; the duct. the secretory coilthe secretory coil: 3 cell types:: 3 cell types:

clear (secretory) – pyramidal, with abundent mitochondria, a clear (secretory) – pyramidal, with abundent mitochondria, a lipofuscin cell granule;lipofuscin cell granule;

dark (mucoid) – cuboidal or pyramidal, with dark granules;dark (mucoid) – cuboidal or pyramidal, with dark granules; myoepithelial cells;myoepithelial cells;

the ductthe duct:: in the dermis: 2 layers: basal cells (outer ring), luminal cells in the dermis: 2 layers: basal cells (outer ring), luminal cells

(inner ring); membrane;(inner ring); membrane; in the epidermis: 1 layer – luminal cells;in the epidermis: 1 layer – luminal cells; opens directly onto the skin surface.opens directly onto the skin surface.

Eccrine sweat glandEccrine sweat gland

Histology of the skin appendagesHistology of the skin appendages

Apocrine sweat glandApocrine sweat gland limited to the axillae, nipples, perineum and genitalia, limited to the axillae, nipples, perineum and genitalia,

groin, periumbilical area;groin, periumbilical area; larger than eccrine gland;larger than eccrine gland; opens in the folliculary duct.opens in the folliculary duct.

Apoeccrine sweat glandApoeccrine sweat gland 50% of axillary glands in the adults with axillary 50% of axillary glands in the adults with axillary

hyperhydrosis;hyperhydrosis; a long duct which opens directly into skin surface.a long duct which opens directly into skin surface.

Apocrine sweat glandApocrine sweat gland


Sebaceous glandSebaceous gland

distributed in large numbers in the face, scalp, chest, distributed in large numbers in the face, scalp, chest,

upper back;upper back;

associated with hair follicles;associated with hair follicles;

microscopically: multilobed, with cells with small dark microscopically: multilobed, with cells with small dark

nucleus and a foamy cytoplasm;nucleus and a foamy cytoplasm;

in E.M.: peripheral cells with tonofilaments and few lipid in E.M.: peripheral cells with tonofilaments and few lipid

droplets; central cells full of lipids; excretory duct with droplets; central cells full of lipids; excretory duct with

stratified squamous epithelium.stratified squamous epithelium.

Sebaceous glandSebaceous gland


HairHair:: distributed on all areas of the skin, except the palms, soles distributed on all areas of the skin, except the palms, soles

and portions of the genitalia;and portions of the genitalia; types of hair:types of hair:

lanugo hairs: fine, long hairs covering the fetus;lanugo hairs: fine, long hairs covering the fetus; vellus hairs: fine, short, unmedullated;vellus hairs: fine, short, unmedullated; indeterminate scalp hairs: under 1 cm in length; fine, indeterminate scalp hairs: under 1 cm in length; fine,

hypopigmented (between 11 and 16 years);hypopigmented (between 11 and 16 years); terminal hairs: longer than 1 cm, coarse medullated, terminal hairs: longer than 1 cm, coarse medullated,

pigmented (in adults on the scalp, eyebrows, pigmented (in adults on the scalp, eyebrows, eyelashes, beard, axillae, pubic region);eyelashes, beard, axillae, pubic region);

Skin appenSkin appenddaaggeses


HairHair:: in a longitudinal section:in a longitudinal section:

the lower portion (hair bulb):the lower portion (hair bulb): dermal hair papilla with capillary loops;dermal hair papilla with capillary loops; hair matrix;hair matrix; hair;hair; inner root sheath and outer root sheat.inner root sheath and outer root sheat.

the middle portion (isthmus) – from the the middle portion (isthmus) – from the attachment of the arrector pili muscle to the attachment of the arrector pili muscle to the entrance of sebaceous duct;entrance of sebaceous duct;

the upper portion (infundibulum) – above the the upper portion (infundibulum) – above the entrance of the sebaceous duct;entrance of the sebaceous duct;


HairHair:: the hair shaft (in horizontal section):the hair shaft (in horizontal section):

medulla;medulla; cortex;cortex; inward to outward. inward to outward. hair cuticle.hair cuticle.

the inner root sheath (3 concentric layers):the inner root sheath (3 concentric layers): inner root sheath cuticle;inner root sheath cuticle; Huxley layer;Huxley layer; Henle layer.Henle layer.

the outer root sheath – a downward extension of the the outer root sheath – a downward extension of the epidermis;epidermis;

vitreous layer;vitreous layer; fibrous root sheath.fibrous root sheath.


NailNail:: the the matrixmatrix: underlies the proximal nail fold but some : underlies the proximal nail fold but some

extends under the nail plate; produce nail plate;extends under the nail plate; produce nail plate; the the nail bednail bed: an epithelium that produces a minimal : an epithelium that produces a minimal

amount of keratin, adherent to the bottom of the nail plate;amount of keratin, adherent to the bottom of the nail plate; the the nail platenail plate: grow out from the nail matrix; rests on the : grow out from the nail matrix; rests on the

nail bed; contain hard keratin; normally – thin and nail bed; contain hard keratin; normally – thin and translucent;translucent;

the the nail foldsnail folds: 1 proximal, 2 laterals;: 1 proximal, 2 laterals; the the hyponychiumhyponychium: extends from the nail bed to the distal : extends from the nail bed to the distal

groove;groove; cuticlecuticle: extension of dorsal epidermal stratum corneum on : extension of dorsal epidermal stratum corneum on

the nail plate; seals proximal nail fold.the nail plate; seals proximal nail fold.

Cutaneous vasculatureCutaneous vasculatureBlood vesselsBlood vessels:: vascular network: vertically distributing and collecting vessels and vascular network: vertically distributing and collecting vessels and

horizontal plexuses;horizontal plexuses;

the the subcutaneous plexussubcutaneous plexus: small branches from musculocutaneous : small branches from musculocutaneous arteries that penetrate the subcutaneous fat;arteries that penetrate the subcutaneous fat;

the the subpapillary plexussubpapillary plexus: arterioles that ascend into the dermis and : arterioles that ascend into the dermis and form an horizontal arteriolar plexus;form an horizontal arteriolar plexus;

the the superficial plexussuperficial plexus (papillary plexus): arterioles became capillary (papillary plexus): arterioles became capillary loops in the dermal papillae;loops in the dermal papillae;

the layers of the vessels: intima (endothelial cells), internal elastic the layers of the vessels: intima (endothelial cells), internal elastic lamina, media (muscle cells); adventitia (connective tissue);lamina, media (muscle cells); adventitia (connective tissue);

the glomus: a special arterio-venous shunt located within the reticular the glomus: a special arterio-venous shunt located within the reticular dermis in certain areas (the pads and nail beds of the fingers and dermis in certain areas (the pads and nail beds of the fingers and toes, the ears, in the center of the face).toes, the ears, in the center of the face).

Cutaneous vasculatureCutaneous vasculature

Cutaneous lymphaticsCutaneous lymphatics:: begin with a blind-ended capillary in the dermal papilla;begin with a blind-ended capillary in the dermal papilla;

a superficial lymphatic plexus in the papillary dermis; a superficial lymphatic plexus in the papillary dermis; postcapillary lymph vessels;postcapillary lymph vessels;

two deeper horizontal plexuses.two deeper horizontal plexuses.

Nerves and receptors of the skinNerves and receptors of the skin

the the nerve networknerve network of the skin contain somatic sensory and of the skin contain somatic sensory and sympathetic autonomic fibers;sympathetic autonomic fibers;

the the sensory fiberssensory fibers alone (free nerve endings) or in alone (free nerve endings) or in association with specialized structures (corpuscular association with specialized structures (corpuscular receptors) are receptors of touch, pressure, itch, pain, receptors) are receptors of touch, pressure, itch, pain, temperature;temperature;

sympathetic motor fiberssympathetic motor fibers innervate the sweat glands, innervate the sweat glands, vascular smooth muscle, the arrector pili muscle, vascular smooth muscle, the arrector pili muscle, sebaceous glands;sebaceous glands;

the the free nerve endingsfree nerve endings (including those associated with (including those associated with Merkel cells) – the most widespread in the skin;Merkel cells) – the most widespread in the skin;

Nerves and receptors of the skinNerves and receptors of the skin

the the corpuscular receptorscorpuscular receptors (capsule and inner core), contain neural (capsule and inner core), contain neural and nonneural components:and nonneural components: Meissner corpuscleMeissner corpuscle: elongated or ovoid mechanoreceptor : elongated or ovoid mechanoreceptor

located in the dermal papillae of digital skin;located in the dermal papillae of digital skin;

mucocutaneous end organsmucocutaneous end organs: located in the lips, eyelid, perianal : located in the lips, eyelid, perianal canal, glans, clitoris;canal, glans, clitoris;

Vater-Pacini corpuscleVater-Pacini corpuscle: ovoid or flattened sphere; lies in the : ovoid or flattened sphere; lies in the deep dermis and hypodermis in weight-bearing surfaces, deep dermis and hypodermis in weight-bearing surfaces, nipple, anogenital region;nipple, anogenital region;

Krause corpuscleKrause corpuscle: irregular round; capsule, fibrillar structure;: irregular round; capsule, fibrillar structure;

Ruffini corpuscleRuffini corpuscle: amielinic fibers, thin capsule.: amielinic fibers, thin capsule.

Physiology of the skinPhysiology of the skin

Process of keratinization (keratin synthesis)Process of keratinization (keratin synthesis)

is a form of terminal differentiation of the is a form of terminal differentiation of the keratinocyteskeratinocytes;;

the cytoskeleton of all mammalian cells is composed of the cytoskeleton of all mammalian cells is composed of

three filament systems:three filament systems:

microfilaments (6 nm);microfilaments (6 nm);

intermediate filaments (8-10 nm);intermediate filaments (8-10 nm);

microtubules (25 nm);microtubules (25 nm);

the keratins are members of the intermediate filaments;the keratins are members of the intermediate filaments;

the process of keratinization:the process of keratinization:

degenerative phenomena;degenerative phenomena;

synthetic processes;synthetic processes;


degenerative phenomena: of nucleus, cellular organelles, degenerative phenomena: of nucleus, cellular organelles, cell envelope, desmosomes;cell envelope, desmosomes;

synthetic processes:synthetic processes: keratin intermediate filament formation;keratin intermediate filament formation; synthesis of keratinosomes;synthesis of keratinosomes; cell envelope (CE) formation – cornified envelope; cell envelope (CE) formation – cornified envelope; keratohyaline granules proteins synthesis;keratohyaline granules proteins synthesis; keratin synthesis;keratin synthesis;

keratins family: 20 epithelial keratins, 10 hair keratins; type keratins family: 20 epithelial keratins, 10 hair keratins; type I (acidic), type II (neutral-basic); molecular masse between I (acidic), type II (neutral-basic); molecular masse between 40 and 68 kDa);40 and 68 kDa);


each of the keratins is the product of a unique gene;each of the keratins is the product of a unique gene; the keratins are expressed as pairs with one member of the keratins are expressed as pairs with one member of

each subfamily;each subfamily; soft keratinization (skin);soft keratinization (skin); hard keratinization (hair, nail, lingual papillae).hard keratinization (hair, nail, lingual papillae).

The control of keratinizationThe control of keratinization:: factors of activation: oestrogens, corticosteroids, timic factors of activation: oestrogens, corticosteroids, timic

extracts, mechanical pression, ultraviolet radiation;extracts, mechanical pression, ultraviolet radiation; factors of inhibition: vitamin A, thyroid hormones.factors of inhibition: vitamin A, thyroid hormones.

MelanogenesisMelanogenesis

Cells implicated – melanocytesCells implicated – melanocytes- Epidermal melanin unitEpidermal melanin unit: a melanocyte and 36 keratinocytes : a melanocyte and 36 keratinocytes

to which the pigment is transferred;to which the pigment is transferred;- the keratinocytes phagocytize the melanosome – laden the keratinocytes phagocytize the melanosome – laden

dendritic tips of the melanocyte (apocopation);dendritic tips of the melanocyte (apocopation);- there is no differences in the number of melanocytes per there is no differences in the number of melanocytes per

square millimeter of the skin on the same anatomic region of square millimeter of the skin on the same anatomic region of black and white patients;black and white patients;

- a difference in melanocyte density for various regions of the a difference in melanocyte density for various regions of the body: the lowest number on the trunk and arm, the highest body: the lowest number on the trunk and arm, the highest on the face;on the face;

- the major difference is in the activity of individual the major difference is in the activity of individual melanocytes; in black skin, larger, more dendritic, with melanocytes; in black skin, larger, more dendritic, with greater quantity of melanin, than in white skin.greater quantity of melanin, than in white skin.


MelanosomesMelanosomes:: highly organized organelles that contain:highly organized organelles that contain:

structural matrix proteins;structural matrix proteins; tyrosinase;tyrosinase; several proteins of unknown structure;several proteins of unknown structure;

4 stages (I-IV) in melanosome development:4 stages (I-IV) in melanosome development: sphericalspherical: contains filaments with a distinct periodicity;: contains filaments with a distinct periodicity; ellipsoidalellipsoidal: oval in shape, with numerous parallel : oval in shape, with numerous parallel

longitudinal fillaments, no melanin depostion;longitudinal fillaments, no melanin depostion; partially melanizedpartially melanized: the internal structure partially : the internal structure partially

obscured by the deposition of melanin pigment;obscured by the deposition of melanin pigment; completely melanizedcompletely melanized: melanin deposited throughout : melanin deposited throughout

the structure;the structure;


the melanosomes pass from the perinuclear area of the the melanosomes pass from the perinuclear area of the melanocyte to the dendrites and progress from stage I to melanocyte to the dendrites and progress from stage I to stage IV;stage IV;

the relationship between skin color and melanosomes:the relationship between skin color and melanosomes: in black skin they are larger, individually dispersed in in black skin they are larger, individually dispersed in

the keratinocytes;the keratinocytes; in white skin they are smaller, aggregated into groups in white skin they are smaller, aggregated into groups

of two or three;of two or three; the degradation of melanosomes in keratinocytes by the degradation of melanosomes in keratinocytes by

lisosomal enzymes with a faster rate in white skin and lisosomal enzymes with a faster rate in white skin and slowly in black skin. slowly in black skin.

MelanogenesisMelanogenesisMelanin synthesisMelanin synthesisThe classic Mason-Raper pathwayThe classic Mason-Raper pathway::

tyrosinase tyrosinasetyrosinase tyrosinase

tyrosine tyrosine → → dopa → → dopa quinone → leucodopachrome → → dopa → → dopa quinone → leucodopachrome dopachrome conversion factordopachrome conversion factor tyrosinasetyrosinase

→ → dopachrome → → 5,6 – dihydroxyindole → → indole-5,6dopachrome → → 5,6 – dihydroxyindole → → indole-5,6 - quinone → → melanochrome → melanin- quinone → → melanochrome → melanin

Dopachome oxyreductase (dopachrome tautomerase) – Dopachome oxyreductase (dopachrome tautomerase) – other regulatory factor.other regulatory factor.

Forms of melanin:Forms of melanin: eumelanin – brown to black in color, with Mason-Raper eumelanin – brown to black in color, with Mason-Raper

pathway of synthesis;pathway of synthesis; phaeomelanin – yelow-red in color, with another pathway phaeomelanin – yelow-red in color, with another pathway

of synthesis;of synthesis; mixed type of melanins.mixed type of melanins.


The control of melanogenesisThe control of melanogenesis

Melanocyte-stimulating hormones (MSH, melanotropins) Melanocyte-stimulating hormones (MSH, melanotropins) αα, , ββ, , γγ::

MelanogenesisMelanogenesisUltraviolet (UV) radiationUltraviolet (UV) radiation the spectrum of UV radiation:the spectrum of UV radiation:

UVC (200-290 nm);UVC (200-290 nm); UVB (290-320 nm);UVB (290-320 nm); UVA (320-400 nm).UVA (320-400 nm).

immediate pigmentary darkening: within minutes of sun immediate pigmentary darkening: within minutes of sun exposure, fades within 6-8 hours; produced by UVA and visible exposure, fades within 6-8 hours; produced by UVA and visible light, as a result of an oxidation of persisting melanin or its light, as a result of an oxidation of persisting melanin or its precursors;precursors;

delayed tanning: is apparent within 48-72 hours, produced by delayed tanning: is apparent within 48-72 hours, produced by UVB and UVA, as a result of new melanin production.UVB and UVA, as a result of new melanin production.

Other factors of stimulationOther factors of stimulation: estrogens, estrogens and : estrogens, estrogens and progesterone, prostaglandins Eprogesterone, prostaglandins E2 2 and Dand D22, copper, nitrogen , copper, nitrogen mustard, ACTH, PUVA;mustard, ACTH, PUVA;

Factors that inhibit melanogenesisFactors that inhibit melanogenesis: vitamins B: vitamins B1 1 and C, silver, and C, silver, hydroquinone.hydroquinone.

Physiology of skin appendagesPhysiology of skin appendages

HairHair Hair growth rate: 0.35-0.37 mm/ dayHair growth rate: 0.35-0.37 mm/ day Hair cycleHair cycle: regular cycles of growth and shedding; 3 phases : regular cycles of growth and shedding; 3 phases

of follicular activity:of follicular activity: anagenanagen: the growth stage (3-5 years on the scalp);: the growth stage (3-5 years on the scalp); catagencatagen: the degenerative stage, with conversion from : the degenerative stage, with conversion from

active growth to the resting phase (few days on the active growth to the resting phase (few days on the scalp);scalp);

telogentelogen: the resting stage (3-4 month on the scalp);: the resting stage (3-4 month on the scalp);

100 hairs may be shed from the scalp every day100 hairs may be shed from the scalp every day


Hair:Hair: Regulation of the hair growthRegulation of the hair growth::

genetic influences for normal growth of hairs on genetic influences for normal growth of hairs on different anatomic locations;different anatomic locations;

hormonal influences:hormonal influences: androgens “upregulate” the pubic hair, axillary hair, androgens “upregulate” the pubic hair, axillary hair,

beard hair and “downregulate” genetically beard hair and “downregulate” genetically predisposed scalp hair follicles in andro-genetic predisposed scalp hair follicles in andro-genetic alopecia;alopecia;

corticosteroids, the ACTH, thyroid hormones, corticosteroids, the ACTH, thyroid hormones, somatothrope hormone stimulate the hair growth;somatothrope hormone stimulate the hair growth;

estrogens stimulate indirectly the axillary and pubic estrogens stimulate indirectly the axillary and pubic hair;hair;

other factors: UV and infrared radiation stimulate the other factors: UV and infrared radiation stimulate the hair growth; Bi, cytostatics, inhibits the hair growth.hair growth; Bi, cytostatics, inhibits the hair growth.


NailNail

the average rate of growth of the thumbnail: 0.10-0.12 the average rate of growth of the thumbnail: 0.10-0.12 mm/ day; finger nails: 0.5-1.2 mm/ week;mm/ day; finger nails: 0.5-1.2 mm/ week;

fingernails grow faster than toenails;fingernails grow faster than toenails;

the hard keratin of the nail plate is formed in the nail the hard keratin of the nail plate is formed in the nail matrix;matrix;

functions of the nailfunctions of the nail::

strength and protection for the terminal phalanx;strength and protection for the terminal phalanx;

help with fine touch;help with fine touch;

handling of small objects;handling of small objects;

the esthetic role.the esthetic role.


Eccrine sweat glandEccrine sweat gland type of secretiontype of secretion: merocrine (the integrity of the secretory : merocrine (the integrity of the secretory

cell after secretion);cell after secretion); the responsiveness of the sweat gland to cholinergic the responsiveness of the sweat gland to cholinergic

agents, agents, αα and and ββ adrenergic stimulants and other adrenergic stimulants and other neurotransmiters (VIP, ATP);neurotransmiters (VIP, ATP);

periglandular acetylcholine – the major stimulant of eccrine periglandular acetylcholine – the major stimulant of eccrine sweat secretion;sweat secretion;

sweat formationsweat formation in 2 steps: in 2 steps: secretion of primary fluid with nearly isotonic NaCl secretion of primary fluid with nearly isotonic NaCl

concentrations by the secretory coil;concentrations by the secretory coil; reabsorption of NaCl from the primary fluid by the duct reabsorption of NaCl from the primary fluid by the duct

under the influence of aldosterone and antidiuretic under the influence of aldosterone and antidiuretic hormone; sweat becomes hypotonic.hormone; sweat becomes hypotonic.


Eccrine sweat glandEccrine sweat gland composition of eccrine sweatcomposition of eccrine sweat::

inorganic ions: Na, Cl, K, Ca, P, Mg, I, HCOinorganic ions: Na, Cl, K, Ca, P, Mg, I, HCO33, Fe, Zn et , Fe, Zn et al.;al.;

organic compounds: urea, ammonia, amino acids, organic compounds: urea, ammonia, amino acids, proteins, lactate, glucose, piruvate, histamine, proteins, lactate, glucose, piruvate, histamine, bradikinine, immunoglobulins, prostaglandins, vitamine bradikinine, immunoglobulins, prostaglandins, vitamine C, BC, B22, B, B66, K, amphetamine-like substances, proteolytic , K, amphetamine-like substances, proteolytic enzymes, et. al.;enzymes, et. al.;

pH between 4.0 and 6.8;pH between 4.0 and 6.8; control of eccrine sweat secretioncontrol of eccrine sweat secretion::

thermal factors: sweating all over the body, especially thermal factors: sweating all over the body, especially the chest, back, forehead, scalp and axillae;the chest, back, forehead, scalp and axillae;

physic exercise: sweating mainly on the palms, soles physic exercise: sweating mainly on the palms, soles and axillae.and axillae.


Apocrine sweat glandApocrine sweat gland type of secretion: holomerocrine or decapitation secretion type of secretion: holomerocrine or decapitation secretion

(the luminal part of the cell is lost);(the luminal part of the cell is lost); composition of secretion: apocrine sweat is milky, viscid; composition of secretion: apocrine sweat is milky, viscid;

the chemical composition is little known because of the chemical composition is little known because of difficulties in collecting a pure secretion (mixed with sebum difficulties in collecting a pure secretion (mixed with sebum and eccrine sweat);and eccrine sweat);

control of secretioncontrol of secretion:: emotional factors (only after puberty) the secretion can emotional factors (only after puberty) the secretion can

be stimulated by epinephrine or norepinephrine; be stimulated by epinephrine or norepinephrine; adrenergic-neuron blocking agents and adrenergic-adrenergic-neuron blocking agents and adrenergic-receptor blocking drugs inhibit apocrine sweating;receptor blocking drugs inhibit apocrine sweating;

hormonal factors: the development of the apocrine hormonal factors: the development of the apocrine glands is dependent on the sex hormones and not the glands is dependent on the sex hormones and not the maintenance of their functional activity.maintenance of their functional activity.


Sebaceous glandSebaceous gland type of secretion: holocrine (entire sebaceous cell break type of secretion: holocrine (entire sebaceous cell break

down to form the secretion);down to form the secretion); composition of sebumcomposition of sebum: squalene, wax esters, triglycerides, : squalene, wax esters, triglycerides,

fatty acids, cholesterol, cholesterol esters;fatty acids, cholesterol, cholesterol esters; control of sebum secretioncontrol of sebum secretion::

androgenic hormones stimulate sebaceous gland, androgenic hormones stimulate sebaceous gland, especially dihydrotestosterone;especially dihydrotestosterone;

exogenous estrogens lower the sebum secretion when exogenous estrogens lower the sebum secretion when they are administrated in a great quantity;they are administrated in a great quantity;

fasting decrease the sebum secretion;fasting decrease the sebum secretion; exogenous retinoids supress the sebum secretion by exogenous retinoids supress the sebum secretion by

inhibiting sebaceous cells;inhibiting sebaceous cells; damage to the epidermis inhibits the sebaceous glands damage to the epidermis inhibits the sebaceous glands

underneath the wound.underneath the wound.

Protective functions of the skinProtective functions of the skin

protectionprotection against the loss of essential body fluidsagainst the loss of essential body fluids: the role : the role of epidermis and horny layer;of epidermis and horny layer;

protection against the entrance of toxic agentsprotection against the entrance of toxic agents: stratum : stratum corneum restricts the absorption of selected classes of corneum restricts the absorption of selected classes of molecules and serves as a reservoir for exogenous toxic molecules and serves as a reservoir for exogenous toxic and nontoxic agents;and nontoxic agents;

protection against the entrance of microorganismsprotection against the entrance of microorganisms:: the structural integrity of horny layer;the structural integrity of horny layer; the desquamation: remove adherent microorganisms;the desquamation: remove adherent microorganisms; sebaceous lipids: antibacterial effects;sebaceous lipids: antibacterial effects; biochemical defenses: the acid environment (pH of 5 to biochemical defenses: the acid environment (pH of 5 to

6.5), cytokines, prostaglandins, antioxidants, enzyme 6.5), cytokines, prostaglandins, antioxidants, enzyme systems;systems;

Langerhans cells and T lymphocytes;Langerhans cells and T lymphocytes;

Protective functions of the skinProtective functions of the skin

protection against damage from UV radiationprotection against damage from UV radiation:: the stratum corneum;the stratum corneum; melanin barrier;melanin barrier;

protection against damage from mechanical agentsprotection against damage from mechanical agents:: stratum corneum;stratum corneum; dermis and hypodermis;dermis and hypodermis; protection against environmental temperature: the role protection against environmental temperature: the role

of the skin in the maintenance of a constant body of the skin in the maintenance of a constant body temperature:temperature: the effector role of the skin in thermoregulation: skin the effector role of the skin in thermoregulation: skin

thermoreceptors, skin vasculature, sweat gland thermoreceptors, skin vasculature, sweat gland responses with heat transfer from the skin to the responses with heat transfer from the skin to the environment by evaporation of the sweat;environment by evaporation of the sweat;

protection against damage from low-voltage electric protection against damage from low-voltage electric current: the stratum corneum.current: the stratum corneum.

Skin immune system (SIS)Skin immune system (SIS)

Cellular components of SISCellular components of SIS lymphocyteslymphocytes: T lymphocytes (T helper/ inducer cells, T : T lymphocytes (T helper/ inducer cells, T

supressor cells, T cytotoxic cells) B lymphocytes;supressor cells, T cytotoxic cells) B lymphocytes; null cellsnull cells (nonT, nonB): NK (natural killer) and K (killer) (nonT, nonB): NK (natural killer) and K (killer)

cells;cells; Langerhans cellsLangerhans cells and other dendritic cells; and other dendritic cells; keratinocyteskeratinocytes;; cells of the monocyte/ macrophage systemcells of the monocyte/ macrophage system: monocytes, : monocytes,

macrophages;macrophages; granulocytesgranulocytes (neutrophils, eosinophils, basophils); (neutrophils, eosinophils, basophils); mast cellsmast cells..

Skin immune system (SIS)Skin immune system (SIS)

Molecular components of SISMolecular components of SIS antigens and haptens;antigens and haptens; antibodies (immunoglobulins);antibodies (immunoglobulins); complement;complement; cytokines;cytokines; adhesion molecules;adhesion molecules; histocompatibility antigens (HLA).histocompatibility antigens (HLA).

Sensory functionSensory function

the capacity of the skin to detect changes in the the capacity of the skin to detect changes in the

surrounding environment and transmit these informations surrounding environment and transmit these informations

to central nervous system for processing;to central nervous system for processing;

sensory fibers may contain one or various neuropeptides sensory fibers may contain one or various neuropeptides

that may act as mediators of inflammation.that may act as mediators of inflammation.

Basic pathologic reactions of Basic pathologic reactions of the skinthe skin

Pathologic reactions in the epidermisPathologic reactions in the epidermis

Disturbances of epidermal cell kineticsDisturbances of epidermal cell kinetics

AcanthosisAcanthosis: a broadening of the stratum spinosum by an : a broadening of the stratum spinosum by an increase of cell population.increase of cell population.

GranulosisGranulosis: a thickening of the granular cell layer.: a thickening of the granular cell layer.

HyperkeratosisHyperkeratosis: a thickening of the horny layer by an : a thickening of the horny layer by an increased production or a reduced desquamation of increased production or a reduced desquamation of corneocytes.corneocytes.

AtrophyAtrophy of the epidermis: a diminution of the germinative cell of the epidermis: a diminution of the germinative cell volume and a flattening of the rete ridges.volume and a flattening of the rete ridges.

Pathologic reactions in the epidermisPathologic reactions in the epidermisDisturbances of epidermal cell differentiationDisturbances of epidermal cell differentiationParakeratosisParakeratosis: a falty and accelerated cornification leads to a : a falty and accelerated cornification leads to a

retention of pyknotic nuclei of epidermal cells; the stratum retention of pyknotic nuclei of epidermal cells; the stratum granulosum is rudimentary or may not be present and the granulosum is rudimentary or may not be present and the horny layer contain pyknotic nuclei and other organelles in a horny layer contain pyknotic nuclei and other organelles in a dense cytoplasmic net of keratin fibrils.dense cytoplasmic net of keratin fibrils.

DiskeratosisDiskeratosis: a premature cornification of individual cells within : a premature cornification of individual cells within the viable layers of the epidermis.the viable layers of the epidermis.

Dyskeratotic cells: an eosinophillic cytoplasm, a pyknotic Dyskeratotic cells: an eosinophillic cytoplasm, a pyknotic nucleus, keratin filaments arranged in perinuclear nucleus, keratin filaments arranged in perinuclear aggregates aggregates → a breakdown of the cytoplasmic skeleton → a → a breakdown of the cytoplasmic skeleton → a loss of the ability of the cell to adjust its shape and form → loss of the ability of the cell to adjust its shape and form → the cell tend to round up and lose its attachements to the the cell tend to round up and lose its attachements to the surrounding cells.surrounding cells.

Dyskeratosis – associated with acantholysis.Dyskeratosis – associated with acantholysis.

Hiperkeratosis, acanthosis, agranulosis, parakeratosisHiperkeratosis, acanthosis, agranulosis, parakeratosis

Parakeratoza, agranulozaParakeratoza, agranuloza

DiskeratozaDiskeratoza

Disturbances of epidermal coherenceDisturbances of epidermal coherence

AcantholysisAcantholysis: a primary loss of cohesion of epidermal cells; initially a : a primary loss of cohesion of epidermal cells; initially a

separation of the interdesmosomal regions of the cell membranes of separation of the interdesmosomal regions of the cell membranes of

keratinocytes followed by splitting and disappearance of desmosomes; the keratinocytes followed by splitting and disappearance of desmosomes; the

cells round up and intercellular gaps and slits result; the influx of a serous cells round up and intercellular gaps and slits result; the influx of a serous

exudate from the dermis leads to a cavity; the cells remain metabollicaly exudate from the dermis leads to a cavity; the cells remain metabollicaly

active for some time; degeneration and cell death active for some time; degeneration and cell death → a secondary → a secondary

phenomena; ex. pemphigus vulgaris.phenomena; ex. pemphigus vulgaris.

SpongiosisSpongiosis: a secondary loss of cohesion between epidermal cells due to the : a secondary loss of cohesion between epidermal cells due to the

influx of a serous exudate from the dermis into the intercellular influx of a serous exudate from the dermis into the intercellular

compartment of the epidermis; epidermal cells remain in contact with each compartment of the epidermis; epidermal cells remain in contact with each

other only at the sites of desmosomes and acquire a stellate appearance.other only at the sites of desmosomes and acquire a stellate appearance.

Spongiform vesicle: individual cells rupture and lyse - microcavities; ex. Spongiform vesicle: individual cells rupture and lyse - microcavities; ex.

eczema.eczema.

Spongiform pustule: the migration of leukocytes within the epidermis v Spongiform pustule: the migration of leukocytes within the epidermis v

separation of epidermal cells and subsequent destruction; ex. psoriasis.separation of epidermal cells and subsequent destruction; ex. psoriasis.

AcantholysisAcantholysis

SpongiosisSpongiosis

Disturbance of dermal-epidermal cohesionDisturbance of dermal-epidermal cohesion

Epidermolytic blisteringEpidermolytic blistering: a cytolysis of basal cells; ex. : a cytolysis of basal cells; ex. epidermolysis bullosa simplex;epidermolysis bullosa simplex;

Junctional blisteringJunctional blistering: a cleft formation through the lamina : a cleft formation through the lamina lucida, accompaned by un influx of a serous exudate from lucida, accompaned by un influx of a serous exudate from the dermal vessels; ex. bullous pemphigoid.the dermal vessels; ex. bullous pemphigoid.

Dermolytic blisteringDermolytic blistering: a dermal-epidermal separation below : a dermal-epidermal separation below the basal lamina; ex. recessive epidermolysis bullosa, the basal lamina; ex. recessive epidermolysis bullosa, dermatitis herpetiformis, porphyria cutanea tarda.dermatitis herpetiformis, porphyria cutanea tarda.

Pathologic reactions in the dermisPathologic reactions in the dermis

Inflammatory reactionsInflammatory reactions vasodilatation;vasodilatation; increased permeability and edema;increased permeability and edema; cellular infiltration:cellular infiltration:

acute: polymorphonuclear leukocytic infiltrate;acute: polymorphonuclear leukocytic infiltrate; chronic nonspecific: lymphohistiocytic;chronic nonspecific: lymphohistiocytic; chronic specific: tuberculosis (giant cells, epithelioid cells, chronic specific: tuberculosis (giant cells, epithelioid cells,

lymphocytes, caseation), leprosy (foamy histiocytes), syphilis lymphocytes, caseation), leprosy (foamy histiocytes), syphilis (plasmocytes) et al.(plasmocytes) et al.

HemorrhageHemorrhage

HyperplasiaHyperplasia (proliferative processes) (proliferative processes)

AtrophyAtrophy (atrophic processes) (atrophic processes)

NecrosisNecrosis (a death of the dermis) (a death of the dermis)

Degenerative processesDegenerative processes: fibrinoid, amiloid, mucin accumulation et al. : fibrinoid, amiloid, mucin accumulation et al.

Pathologic reactions in the hypodermisPathologic reactions in the hypodermis

Inflammatory processesInflammatory processes

NecrosisNecrosis

LipogranulomaLipogranuloma

HyperplasiaHyperplasia

Basic skin lesionsBasic skin lesions

MaculeMacule

a circumscribed, flat lesion that differ from the surrounding a circumscribed, flat lesion that differ from the surrounding normal skin by its color; the size and shape are variable.normal skin by its color; the size and shape are variable.

Types of maculesTypes of macules:: by vascular abnormalities:by vascular abnormalities:

erythematouserythematous (by capillary dilatation): red in color, (by capillary dilatation): red in color, reduced by diascopy; ex. psoriasis, eczema, lupus reduced by diascopy; ex. psoriasis, eczema, lupus erythematosus et. al;erythematosus et. al;

purpuricpurpuric (by extravasation of the red blood cells): red- (by extravasation of the red blood cells): red-violet violet → yellow-green → brown; nonreduced by → yellow-green → brown; nonreduced by diascopy; petechiae (small), ecchymoses (larger) diascopy; petechiae (small), ecchymoses (larger) sugillation (“black and blue”); vibices (linear); ex. sugillation (“black and blue”); vibices (linear); ex. purpura.purpura.

MaculeMacule by melanin abnormalitiesby melanin abnormalities::

hiperpigmentationhiperpigmentation (excess of melanin): brown in color; ex. (excess of melanin): brown in color; ex. freckles, naevi, chloasma.freckles, naevi, chloasma.

hypopigmentationhypopigmentation – – depigmentationdepigmentation (lack of pigment (lack of pigment production): white in color; ex. albinism, vitiligo, pityriasis production): white in color; ex. albinism, vitiligo, pityriasis versicolor;versicolor;

artificialartificial: by others pigmentary substances; ex. tatoos, : by others pigmentary substances; ex. tatoos, carotenaemia, jaundice, licopenaemia.carotenaemia, jaundice, licopenaemia.

PatchPatch: a large macule with some surface change – slight scale : a large macule with some surface change – slight scale or fine wrinkling; ex. psoriasis, eczema.or fine wrinkling; ex. psoriasis, eczema.

a small, solid, elevated skin lesion less than 0.5 cm in diameter; a small, solid, elevated skin lesion less than 0.5 cm in diameter; oblique lighting with a flashlight in a darkened room detect a oblique lighting with a flashlight in a darkened room detect a slight elevation;slight elevation;

The shapeThe shape of the papule: of the papule: acuminate (pointed): miliaria rubra;acuminate (pointed): miliaria rubra; dome-shaped: secondary syphilis;dome-shaped: secondary syphilis; flat-topped: lichen planus.flat-topped: lichen planus.

The colorThe color of the papule: red, copper, violaceous, yellow et. al. of the papule: red, copper, violaceous, yellow et. al.

Hystological typesHystological types:: epidermalepidermal (the result of an increase in the number of epidermal (the result of an increase in the number of epidermal

cells): verruca plana (plane warts);cells): verruca plana (plane warts); dermaldermal (the result of an infiltrate in the dermis): secondary (the result of an infiltrate in the dermis): secondary

syphilis;syphilis; dermal-epidermal dermal-epidermal ( a hyperplasia of cellular components of the ( a hyperplasia of cellular components of the

epidermis and an infiltrate in the dermis): lichen planus.epidermis and an infiltrate in the dermis): lichen planus.

PapulePapule

WhealWheal a rounded or flat-topped elevated papule (3-4 mm) or plaque a rounded or flat-topped elevated papule (3-4 mm) or plaque

(10-12 cm in diameter), characteristically evanescent, (10-12 cm in diameter), characteristically evanescent, desappearing within hours.desappearing within hours.

The shapeThe shape: round, oval, serpiginous, annular.: round, oval, serpiginous, annular.

The colorThe color: pale red or white (especially in the center).: pale red or white (especially in the center).

The bordersThe borders: sharp, but not stable (move).: sharp, but not stable (move).

HistologyHistology: an edema in the upper portion of the dermis.: an edema in the upper portion of the dermis.

Exemples: urticaria, ocasionally, dermatitis herpetiformis, Exemples: urticaria, ocasionally, dermatitis herpetiformis, bullous pemphigoid.bullous pemphigoid.

DermographismDermographism: a wheal produced by stroking of the skin in : a wheal produced by stroking of the skin in persons with urticaria, or in normal persons.persons with urticaria, or in normal persons.

NoduleNodule

a palpable, round or oval lesion, greater and deep than a a palpable, round or oval lesion, greater and deep than a papule; the consistence is hard, firm, soft or fleshy; the papule; the consistence is hard, firm, soft or fleshy; the surface is smooth, keratotic, ulcerated or fungatic; is surface is smooth, keratotic, ulcerated or fungatic; is warm, painless or painful.warm, painless or painful.

Histological typesHistological types:: epidermalepidermal: keratoacanthoma;: keratoacanthoma; epidermal-dermalepidermal-dermal: mycosis fungoides, lupus vulgaris;: mycosis fungoides, lupus vulgaris; dermaldermal: granuloma annulare;: granuloma annulare; dermal-subdermaldermal-subdermal: erythema nodosum, hypodermitis;: erythema nodosum, hypodermitis; subcutaneoussubcutaneous: lipoma.: lipoma.

GummaGumma: a granulomatous nodular lesion with stadial : a granulomatous nodular lesion with stadial evolution. ex. late syphilis, tuberculosis, the deep evolution. ex. late syphilis, tuberculosis, the deep mycoses.mycoses.

VegetationVegetation: a small, soft and smooth, pediculated elevation, : a small, soft and smooth, pediculated elevation, red in color; can be covered with thick dry scales red in color; can be covered with thick dry scales (keratotic); vegetations are aglomerated in the cauliflower-(keratotic); vegetations are aglomerated in the cauliflower-like masses, with a moist, macerated surface. ex. like masses, with a moist, macerated surface. ex. condylomata acuminata (anogenital warts), common condylomata acuminata (anogenital warts), common warts, pemphigus vegetans, warty tuberculosis.warts, pemphigus vegetans, warty tuberculosis.

LichenificationLichenification: a thickened plaque with accentuated skin : a thickened plaque with accentuated skin margins, produced after repeated rubbing. margins, produced after repeated rubbing.

Histologically: a proliferation of keratinocytes and stratum Histologically: a proliferation of keratinocytes and stratum corneum in combination with changes in the collagen of corneum in combination with changes in the collagen of the underlying dermis. the underlying dermis.

ex. chronic eczema, prurigo, neurodermatitis.ex. chronic eczema, prurigo, neurodermatitis.

TumorTumor

a benign or malignant proliferation of the skin, variable in a benign or malignant proliferation of the skin, variable in color, fleshy, soft, firm or hard.color, fleshy, soft, firm or hard.

exemples: papilloma, keratoachantoma, lipoma, naevi, exemples: papilloma, keratoachantoma, lipoma, naevi, carcinoma, melanoma, sarcoma, et al.carcinoma, melanoma, sarcoma, et al.

VesicleVesicle

an elevated lesion filled with clear fluid, with a diameter an elevated lesion filled with clear fluid, with a diameter less than 0.5 cm.less than 0.5 cm.

Spongiform vesicleSpongiform vesicle – by an intraepidermal interstitial – by an intraepidermal interstitial vesication (intercellular edema and individual cells vesication (intercellular edema and individual cells rupture): eczema.rupture): eczema.

Parenchimatous vesicleParenchimatous vesicle – by a ballon degeneration of the – by a ballon degeneration of the epidermal cells: herpes simplex, herpes zoster (shingles), epidermal cells: herpes simplex, herpes zoster (shingles), varicella.varicella.

BullaBulla

a blister filled with clear fluid greater than 0.5 cm in a blister filled with clear fluid greater than 0.5 cm in diameter; tense or flaccid;diameter; tense or flaccid;

Histological typesHistological types:: superficial bullasuperficial bulla (subcorneal): impetigo; (subcorneal): impetigo; mediummedium (acantholytic) bulla: pemphigus vulgaris; (acantholytic) bulla: pemphigus vulgaris; profoundprofound (subepidermal) bulla: bullous pemphigoid, (subepidermal) bulla: bullous pemphigoid,

dermatitis herpetiformis, porphyria cutanea tarda, bullous dermatitis herpetiformis, porphyria cutanea tarda, bullous erythema multiforme.erythema multiforme.

PustulePustule

a circumscripted, raised lesion filled with a purulent a circumscripted, raised lesion filled with a purulent exudate, white, yellow or greenish-yellow in color; may exudate, white, yellow or greenish-yellow in color; may vary in size and shape.vary in size and shape.

Types:Types: follicular or nonfollicular;follicular or nonfollicular; sterile or bacterian;sterile or bacterian; primary or secondary.primary or secondary.

Exemples: rosacea, acne vulgaris, pustular psoriasis, Exemples: rosacea, acne vulgaris, pustular psoriasis, folliculitis.folliculitis.

ErosionErosion

a moist, usually depressed lesion that results from loss of a moist, usually depressed lesion that results from loss of all or a portion of the viable epidermis; usually do not scar.all or a portion of the viable epidermis; usually do not scar.

primary or secondary (after the rupture of vesicles, bullae, primary or secondary (after the rupture of vesicles, bullae, the denudation of papules).the denudation of papules).

Exemples: primary chancre, eczema, herpes simplex, Exemples: primary chancre, eczema, herpes simplex, pemphigus vulgaris, et al.pemphigus vulgaris, et al.

UlcerationUlceration a destruction of the epidermis and papillary dermis; may a destruction of the epidermis and papillary dermis; may

vary in size and shape; the base is soft or firm; heels with vary in size and shape; the base is soft or firm; heels with scarring;scarring;

ulcer – a chronic ulceration.ulcer – a chronic ulceration. exemples: stasis ulcer, tuberculosis, neoplasms.exemples: stasis ulcer, tuberculosis, neoplasms.

FissureFissure

a thin linear tear in then skin, superficial or profound a thin linear tear in then skin, superficial or profound (painful), by the loss of the extensibility of the skin by (painful), by the loss of the extensibility of the skin by hiperkeratosis or inflamation.hiperkeratosis or inflamation.

exemples: chronic eczema of the hands and feet, exemples: chronic eczema of the hands and feet, perleche.perleche.

ExcoriationExcoriation

a linear or punctate cleavage in the skin as a result of a linear or punctate cleavage in the skin as a result of scrathing in all types of pruritus.scrathing in all types of pruritus.

exemples: pediculosis, scabies, eczema et al.exemples: pediculosis, scabies, eczema et al.

ScaleScale

abnormal shedding or accumulation of horny layer in abnormal shedding or accumulation of horny layer in perceptible flakes; dry, usually whitish.perceptible flakes; dry, usually whitish.

Types of scaleTypes of scale:: pityriasiformpityriasiform (little and thin): pityriasis simplex, pityriasis (little and thin): pityriasis simplex, pityriasis

versicolor;versicolor; psoriasiformpsoriasiform (brittle platelets of several loose layers): psoriasis; (brittle platelets of several loose layers): psoriasis; seborrheicseborrheic (yellow-to-brown, greasy): seborrheic dermatitis; (yellow-to-brown, greasy): seborrheic dermatitis; ichtyosiformichtyosiform (like fish scales): ichthyosis vulgaris; (like fish scales): ichthyosis vulgaris; cuticularcuticular and and lamellarlamellar (thin, relatively large flakes): lamellar (thin, relatively large flakes): lamellar

ichtyosis;ichtyosis; exfoliativeexfoliative (large sheets): erythroderma; (large sheets): erythroderma; follicularfollicular (keratotic plugs, spines, fillaments): keratosis pilaris; (keratotic plugs, spines, fillaments): keratosis pilaris; hystrix-likehystrix-like (little horns): ichthyosis hystrix. (little horns): ichthyosis hystrix.

CrustCrust

liquid debris that has dried on the surface of the skin; liquid debris that has dried on the surface of the skin; result from breakage of vesicles, bullae or pustules; the result from breakage of vesicles, bullae or pustules; the color: color: yellowyellow (dried serum), (dried serum), green or yellow-greengreen or yellow-green (dried (dried purulent exudate), purulent exudate), brown or blackbrown or black (dried blood). (dried blood).

exemples: impetigo, eczema, herpes simplex, herpes exemples: impetigo, eczema, herpes simplex, herpes zoster, ecthyma et al.zoster, ecthyma et al.

Gangrene and sphacelusGangrene and sphacelus

a lesion resulting from a necrosea lesion resulting from a necrose

gangrene: sharply demarcated, blue-black in color;gangrene: sharply demarcated, blue-black in color;

sphacelus: adherent, dry, necrotic membrane or necrotic sphacelus: adherent, dry, necrotic membrane or necrotic

core.core.

exemples: gangrene from arterial occlusion, decubitus exemples: gangrene from arterial occlusion, decubitus

ulcer, furuncle.ulcer, furuncle.

ScarScar

a residual lesion, replacing an ulceration by healing; a residual lesion, replacing an ulceration by healing; dissapearance of normal skin lines and appendages.dissapearance of normal skin lines and appendages.

Types:Types: hypertrophic: prominent, hard;hypertrophic: prominent, hard; atrophic: thin, depressed;atrophic: thin, depressed;

Exemples: herpes zoster, varicella, acne, porphyria cutanea Exemples: herpes zoster, varicella, acne, porphyria cutanea tarda, ecthyma, syphilis, tuberculosis, leprosy, lupus tarda, ecthyma, syphilis, tuberculosis, leprosy, lupus erythematosus et al.erythematosus et al.

AtrophyAtrophy

thining of the skinthining of the skin

epidermal atrophy: the surface is thin and wrinkled, often epidermal atrophy: the surface is thin and wrinkled, often

associated with dermal alteration.associated with dermal alteration.

dermal atrophy: a depression of the skin; may be or not dermal atrophy: a depression of the skin; may be or not

associated with epidermal atrophy.associated with epidermal atrophy.

exemples: lupus erythematosus, striae of pregnancy, exemples: lupus erythematosus, striae of pregnancy,

scleroderma et al.scleroderma et al.

anatomy and histology of the skin. skin – the more large organ in the body surface – 1.5-1.8...

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skin skin

clear cells

cell organelles

flattened cells

melanocytesthe cells

granullar cell layer

ranges of polygonal

skin surface