general pathology basic principles of cellular and organ pathology autogenous pigments jaroslava...
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General Pathology
Basic Principles of Cellular and Organ Pathology
Autogenous Pigments
Jaroslava Dušková
Inst. Pathol. ,1st Med. Faculty, Charles Univ. Prague
PigmentsDefinition:
colored substances in the organism
or environment
PigmentsClassification: endogenous
autogenous hemoproteins derived
exogenous
Autogenous Pigments
- color substances formed in the organism as metabolism products
melanin ceroid lipofuscin
Melanin oculocutaneous
(origin from tyrosine in melanocytes)
neuromelanin - subst. nigra (origin from dopamin)
Melanin - types
eumelanin – insoluble , brown-black
phaeomelanin – soluble, yellow-red
(high sulphur
content)
Melanin - production
Melanocytes
– derived from the neural crest
– present in the basal layer of epidermis,
dermis, hair folicles, mucose membranes,
uveal tract of the eye, meninges, inner ear
– secretory in the contact with the epithelial
cells - cytocrinia
Melanin Functions – 1.
cytoprotective
– light absorption & conversion of the photon
energy into heat
– uvea – absorption of the light retina
protection of light overexposure
– retina - visual acuity preventing light
reflexion from the fundus
Melanin Functions -2.
Ion exchanging capacity
Melanosomes can also act as detoxyfiing and
excretory components accumulating great number
of drugs and toxic component e.g. heavy metals.
Scavengers of the free radicals.
Rarely cytotoxic – photosensibilisation
Melanin - Features
brown
destained with H2O2
reducing AgNO3
Disorders of Melanin PigmentationLack generalized
– total albinism
– parcial albinism
local– vitiligo
– leucoderma
Albinism
autosomal recessive heredity
– tyrosinase deficiency
– tyrosinase positive – melanosomes defect
oculo-cutaneous albinoidism – dominant
inheritance
Disorders of Melanin PigmentationLack generalized
– total albinism
– parcial albinism
local– vitiligo
– leucoderma
Vitiligo familial aggregation
polygenic nature
association with other
autoimmune diseases (DM,
thyroiditis, gastritis)
ab against tyrosinase in the serum
autoreact . T- cellular cytotoxicity
Disorders of Melanin PigmentationLack generalized
– total albinism
– parcial albinism
local– vitiligo
– leucoderma
Leucoderma
postinflammatory
circumscribed depigmentation
e.g.
– leucoderma syphyliticum
– leucoderma psoriaticum
Disorders of Melanin PigmentationIncrease generalized
– Adison disease
local– freckles, nevi– chloasma /melasma– melanodermia– melanoma
Disorders of Melanin PigmentationIncrease generalized
– Adison disease
local– freckles, nevi– chloasma– melanodermia– melanoma
Disorders of Phenylalanine and Tyrosine Metabolism
1. Phenylalanine hydroxylase PHENYLKETONURIA
2. Homogentisic acid oxydase
ALKAPTONURIA
3. Tyrosinase ALBINISM
Disorders of Phenylalanine and Tyrosine Metabolism
Phenylalanine Tyrosine
methyl–acetoacetic
acid
DOPA
MELANINNorepinephrineEpinephrine
3
1
2
Homogentisicacid
cc
Ceroid features
– light brown–
PAS +– acidoresistent– Sudan +-
origin – fagocytosis od lipid substances by
macrophages– oxidation of non–saturated lipid acids
Ceroid
localisation – places of erythrocytes destruction
– necroses of adipous tissue
– avitamonosis E
– melanosis coli
– Dubin - Johnson syndrome
Lipochrom
ubiquitous pigment exogenous origin lipid solvent histologically unprovable
Lipofuscin features
– dark brown– Sudan +-– autofluorescence
Lipofuscin origin
– autophagocytosis
"wear and tear" pigment from the accumulation of autophagolysosomes over time.
Lipofuscin localisation
– CNS, epithels, muscles, liver
ATROPHIA FUSCA