Disorders of skin color

DR. Ali El-ethawi Specialist Dermatologist M.B.CH.B , F.I.C.M.S, C.A.B.D

5th class lecture

Normal skin color

is composed of a mixture of four biochromes, (1) melanin (brown). (2) reduced hemoglobin (blue), (3) Oxy hemoglobin (red), (4) carotenoids (yellow ; exogenous from diet) The major skin color determinants: is Melanin which is formed fromtyrosine, via the action of tyrosinase, in the melanosomes of

epidermal melanocytes.

So the visible pigmentation of the skin or hair is a combination of the amount of melanin, type of melanin (eumelanin versus pheomelanin),degree of vascularity, and

presence of carotene. Other materials can be deposited abnormally in the skin leading to pigmentation.

Differences in racial pigmentation

• Not due to differences in melanocyte number but from differences in melanocyte activity.

The epidermal melanin unit

Normal skin color

• Constitutive skin color; There are three basic skin colors( black, white

and brown ) which are determined genetically.

• Inducible skin color ; the normal basic skin color pigmentation can be increased by exposure to UVR or pituitary hormones.

• skin phototype (SPT) .• This is a combination of the constitutive and inducible skin color. (SPT 1- 6)

• The skin phototype is a marker for skin cancer risk and should be recorded at the first patient visit

• Ethnicity is not necessarily a part of the definition, • e.g., African "black" ethnic persons can be SPT- III • and an East Indian Caucasian can be SPT IV or even V.

Disorders of skin color

These disorders are Congenital or acquired, Diffuse or circumscribed, • Isolated or part of a syndrome ,Epidermal or dermal, With or without

inflammation.

Altered skin pigmentation may be caused by• Increased or decreased melanin,• Abnormal melanin distribution,• Decreased hemoglobin,• Deposition of exogenous pigments

Some causes of hypopigmentation

Congenital:1. Circumscribed: e.g; * Piebaldism * Nevus depigmentaosus 2. Generalized: * Albinism * Phenylketonuria * Homocytineuria

Nutritional * Kwashiokor * Selenium deficiency

Endocrine : * Hypopituitarism * Thyroid disease

Secondary to physical trauma : * Burns * Trauma * Post-dermabrasion * Post-laserSecondary to chemical exposure : ( occupational or therapeutic )Monobenzyl ether of hydroquinone;phenol ( certain ); steroids; Azelaic acid; Retionoids.

• Hypopigmenation: almost invariably related to decrease production of

melanin,

• e.g. pityriasis alba, seborrheic dermatitis, albinism, tinea

versicolor, nevus depigmentosus, congenital syndromes

• Depigmenation: almost invariably related to absence of melanocytes

• e.g. vitiligo, piebaldism, scarring (DLE)

Vitiligo

• The word vitiligo may be derived from the Greek vitelius, signifying a "calf's white

patches.“• A chronic disorder with multifactorial, genetic

predisposition and triggering factors such as trauma, sunburn, stress, and systemic illness.

• EPIDEMIOLOGY;

• Incidence; Common, worldwide with a prevalence of 1 % to 2 %• Sex; Equal in both sexes.

• Age of Onset; May begin at any age, but in 50% of the patients develop vitiligo before the age of 20, & the incidence decreases with increasing age.

• Race; All races.

Vitiligo

• Clinically: Milky-white macules of different sizes & shapes gradually spread peripherally.

• Sites; Most common sites are periorificial, face, genitals, mucous membranes, extensor surfaces, hands, and feet .

• Microscopically vitiligo is characterized by complete absence of melanocytes.

• Association ; systemic autoimmune and/or endocrine diseases, and, rarely, malignant melanoma.

• 40% of patients have ocular pigmentary abnormalities

• Wood's light Examination the examination is done in a dark room, accentuates the hypopigmented areas and useful is for examining patients with light complexions.

Vitiligo

• Inheritance; Vitiligo has a genetic background; > 30% had +ve FH. Transmission is most likely polygenic with variable expression.

• Pathogenesis– The autoimmune theory ,melanocytes are destroyed by

certain lymphocytes that have somehow been activated. – The neurogenic hypothesis ,is based on an interaction of the

melanocytes and nerve cells. – The self-destruct hypothesis ,melanocytes are destroyed by

toxic substances formed as part of normal melanin biosynthesis

Types Focal vitiligo ; Usually a solitary macule or a few scattered macules in one area, Segmental vitiligo: Unilateral macules in a dermatomal or quasi-dermatomal

distribution. Acrofacial vitiligo: Depigmentation of the distal fingers and periorificial areas.Generalized vitiligo : (vitiligo vulgaris), the most common pattern. Depigmented patches are widely and

usually symmetrically distributed.Universal vitiligo ; Depigmented macules and patches over most of the body, often

associated with multiple endocrinopathy syndrome.Mucosal vitiligo: Involvement of the mucus membrane.

Differential Diagnosis– Pityriasis alba (slight scaling, fuzzy margins, off-white color).

– Pityriasis versicolor (fine scales with greenish-yellow fluorescence under Wood's lamp, positive KOH.

– Leprosy (endemic areas, off-white color, usually ill-defined anesthetic macules).

– Nevus depigmentosus (stable, congenital, off-white macules, unilateral). – Nevus anemicus (does not enhance with Wood's lamp; does not show erythema after

rubbing). – Tuberous sclerosis : stable, congenital off-white macules ( ash-leaf shape) . – Piebaldism (congenital, white forelock, stable, dorsal pigmented stripe on back, distinctive

pattern with large hyperpigmented macules in the center of the hypomelanotic areas).

– Postinflammatory leukoderma [off-white macules (usually a history of psoriasis or eczema in the same macular area), not so sharply defined].

– Mycosis fungoides (may be confusing as only depigmentation may be present and biopsy is necessary).

Course and Prognosis

• Vitiligo is a chronic disease. • The course is highly variable, but rapid onset followed by a period of

stability or slow progression is most characteristic. • some spontaneous repigmentation Up to 30% of patients• Rapidly progressive vitiligo may quickly lead to

extensive depigmentation with a total loss of pigment in skin and hair, but not eyes.

R x of vitiligo • Sunscreens; Sunscreens help prevent sunburn and thus may lessen photodamage as well as the chance that a

Koebner phenomenon will occur

• Cosmetics ;Many patients, especially patients with focal vitiligo, find cosmetic cover-ups to be a valuable treatment option.

• Topical Corticosteroids ; for limited areas of vitiligo and are often the first line of therapy for children

• Topical Immunomodulators; Topical tacrolimus ointment is effective localized vitiligo particularly on the face and neck.

• Topical Calcipotriol ; produces cosmetically acceptable repigmentation in some patients with vitiligo.

• Pseudocatalase ; Catalase, an enzyme normally found in skin that decreases damage from free radicals, has been reported to be low in the skin of vitiligo patients.

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• Systemic Therapies ; systemic corticosteroids have been used as pulse therapy with variable results and may prevent rapid depigmentation in active disease

• Psoralen and Ultraviolet A Therapy (PUVA) Topical or oral 8-methoxypsoralen combined with UVA (320 to 400 nm) irradiation (PUVA) is effective for treating vitiligo,

• Narrowband Ultraviolet B Radiation (NB –UVB-311 nm) is considered by many to be the first choice for most patients.

• Excimer Laser (308 nm) ; has been recently studied in several trials for its efficacy in treating vitiligo

• Depigmentation; Monobenzyl ether of hydroquinone (Monobenzone 20% cream ) for depigmenting residual normal skin in patients with extensive vitiligo,it is a permanent, irreversible process

• Mini-skingrafting may be a useful technique for refractory and stable segmental vitiligo macules

Albinism

A group of genetic disorder in which there is little or no melanin pigment in skin, hair follicles, and eyes.

Normal number of melanocytes are present but with reduced or absent tyrosinase positivity so, there

is defect in the synthesis of melanin (tyrosinase +ve or –ve)Albinism of the eyes and skin: occulocutaneous albinism (OCA); Albinism can affect the eyes: ocular albinism (OA); The cutaneous phenotype of the various forms of albinism is broad, but the ocular phenotype is reasonably constant in most forms.

• World-wide occurrence.• Albinism is usually a recessive trait.• Clinical features; the whole skin is white &pigment is also lacking In the hair ,iris &retina • The albinos have poor sight , photophobia • &rotary Ocular nystagmus • Complication; development of sun- induced skin tumorseven when they are young .

Pityriasis alba

• It is a common finding (5% of children) that is probably more usual in patients with the atopic diathesis.

• Age; The condition appears in most instances before puberty.• Site ;The most common sites are the face, neck, and arms.• C/F; The lesions begin as a non-specific erythema and gradually become scaly and hypopigmented. • Cause ;The hypopigmentation is transient and caused by mild dermal inflammation. • The condition gradually improves after puberty.• D.DX; vitiligo and tinea versicolor. • Treatment • consists of lubrication.• Mild inflammation responds to mild topical steroids

• Pityriasis versicolor. A. Typical macules are round, very well circumscribed, have fine scale, and are off-white to tan colored..

• B. Confluent macules create scalloped borders. This is a characteristic pattern of macules of pityriasis versicolor.

Tuberous sclerosis. Ash leaf-shaped hypopigmented macules.

Some causes of Hyperpigmentation

Genetic • Freckles• Lentigo• Peutz Jeghers syndrome• Café au lait spots • Xeroderma pigmentosaEndocrine • Addison's disease • Cushing’s syndrome• Pregnancy• Renal failure Metabolic • Biliary cirrhosis• Hemochromatosis• Porphyria Nutritional • Mal absorption• Pellagra

Drugs •Photosensetizing• minocycline •arsenic •psoralens •busulfan •estrogens &progesterone

Postinflammatory• lichen planus•Eczema •Secondary syphilis •Systemic sclerosis •Macular &Lichen amyloidosis •Cryotherapy• Tumors •Malignant melanoma •Pigmented nevi •Acanthosis nigricans •Mastocytosis

• other •Melasma

•Erythema ab igne

Melasma   Melasma (Greek: "a black spot") ,Synonyms: Chloasma (Greek: "a green spot"), mask of pregnancyIt is an acquired light- or dark-brown hyperpigmentation that occurs in the exposed areas, most often

on the face, and results from exposure to sunlight.

Etiology . Genetic factors and UV radiation are the most important causes. Other causes include ; pregnancy, oral contraceptives, estrogen-progesterone therapies, thyroid dysfunction, cosmetics phototoxic and anti -seizure drugs.

Age of Onset; Young adults.Sex; Females > males; about 10% of patients with melasma are men.Race; Melasma is more apparent or more frequent in persons with brown or black constitutive skin

color (persons from Asia, the Middle East, India, South America). Melasma may not resolve after delivery or withdrawal of oral contraceptives. Mild subclinical ovarian dysfunction may be present in some patients . There are three clinical patterns: centrofacial, malar, and mandibularThere are three types based on Wood's light examination: 1.epidermal type. The pigmentation is intensified by Wood's light examination 2. dermal type; The pigmentation does not show enhancement with the Wood's light 3.mixed type

R x of melasma Treatment is aimed at reducing the increased pigmentation that

develops in melasma .

Sun protection;It is essential that the patient use, every morning, an opaque sunblock

containing titanium dioxide and/or zinc oxide; Topical depigmented agents• hydroquinone 2% , 4% cream; • combination of flucinolone , hydroquinone , and tretinoin .• azelaic acid 20% cream;• Kojic acid, retinoids

Others ; chemical peels , laser therapy , and dermabrasion.

Freckles

Freckles or ephelides ;• small, red or light- brown macules• most often found in individuals with fair complexions• are promoted by sun exposure and fade during the winter months. • They are usually confined to the face, arms, and back. • from a few spots on the face to hundreds of confluent macules on the face

and arms. • They usually appear around age 5 year • may be genetically determined (as AD trait) and may recur in successive

generations in similar locations and patterns• Freckle must be differentiated from lentigo simplex• No treatment is necessary• appropriate sun protection is need

Freckles

Lentigo

They are benign discrete hyperpigmented macules

The intensity of the color is not dependent on sun exposure. Appearing at any age and on any part of the body, including the mucosa.The backs of the hands and face (especially the forehead) are favored sites.

Simple lentigo arise most often in Childhood as a few scattered lesions ,most often on areas not exposed to sun, including mucous membrane .

solar lentigo (frequently misnamed "liver spot") appears at a later age, mostly in persons with long-term sun exposure

Simple lentigo and senile lentigo looks alike

RX; lentigenes are best prevented by appropriate sun protection. Cryotherapy, topical tretinoin, and adapalene are effective in the treatment of

solar lentigenes.• Laser like Q-switched ruby 694 nm, Q-switched alexandrite 755nm … are

extremely effective for treating ugly lesions.

Peutz-Jeghers syndrome (PJS)

is characterized by hyperpigmented macules on the lips and oral mucosa and

polyposis of the small intestine.

Erythema ab igne

• brown hyperpigmentation with a reticular pattern develops with Chronic repeated exposure, the eruption initially appears as bands of erythema

• Cause ; Chronic exposure to heat from a wood stove, fireplace, electric blanket, electric heater, hot water bottle, or hot compress

Cafe-au-lait (CAL)spots

• CAL spots are uniformly pale brown macules that vary in size from 0.5 to 20 cm can be found on any cutaneous surface

• They may be present at birth, are 10% to 20% of normal children, and increase in number and size with age.

• in children over 5 years of age : Six or more spots > 1.5 cm in diameter are presumptive evidence of neurofibromatosis (von Reckling hausen's disease) .

• In children under 5 years of age, five or more cafe-au-lait spots greater than 0.5 cm in diameter suggest the diagnosis of neurofibromatosis.

• CAL spots are present in 90% to 100% of patients with von Recklinghausen's disease