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dermatology.Disorders of skin color.(dr.ali)

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  • 1. Disorders of skin color DR. Ali El-ethawi Specialist Dermatologist M.B.CH.B , F.I.C.M.S, C.A.B.D 5 th class lecture
  • 2. Normal skin color
    • is composed of a mixture of four biochromes ,
    • melanin (brown).
    • reduced hemoglobin ( blue ),
    • (3) Oxy hemoglobin (red ),
    • (4) carotenoids (yellow ; exogenous from diet )
    • The major skin color determinants: is Melanin which is formed from
    • tyrosine, 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.
  • 3. Differences in racial pigmentation
    • Not due to differences in melanocyte number but from differences in melanocyte activity.
  • 4. The epidermal melanin unit
  • 5. 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.
  • 6. 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
  • 7. 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-laser Secondary to chemical exposure : ( occupational or therapeutic ) Monobenzyl ether of hydroquinone; phenol ( certain ); steroids; Azelaic acid; Retionoids.
  • 8.  
  • 9.
    • 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)
  • 10. 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.
  • 11. 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.
  • 12.  
  • 13. 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
  • 14.  
  • 15.  
  • 16.  
  • 17. 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.
  • 18.  
  • 19.  
  • 20.  
  • 21. 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).
  • 22. 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 .
  • 23. 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.
    • -------------------------------------------------------------------------------------------------------------------------------------------------------
    • 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
  • 24. 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 tumors
    • even when they are young .
  • 25.  
  • 26. 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
  • 27.
    • 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.
  • 28. Tuberous sclerosis. Ash leaf-shaped hypopigmented macules.
  • 29. Some causes of Hyperpigmentation
    • Genetic
    • Freckles
    • Lentigo
    • Peutz Jeghers syndrome
    • Café au lait spots
    • Xeroderma pigmentosa
    • Endocrine
    • 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
  • 30. Melasma
    •  
    • Melasma (Greek: "a black spot") , Synonyms : Chloasma (Greek: "a green spot"), mask of pregnancy
    • It 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 mandibular
    • There 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
  • 31.  
  • 32. 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.
  • 33. 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
  • 34. Freckles
  • 35. 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.
  • 36. Peutz-Jeghers syndrome (PJS)
    • is characterized by hyperpigmented macules on the lips and oral mucosa and polyposis of the small intestine .
  • 37. 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
  • 38. 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