Disturbances of Pigmentation

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Disturbances of Pigmentation

• Rick Lin, D.O.

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Melanin

• primary pigment producing brown coloration
• Tyrosine tyrosinase melanin- this occurs in
  the melanosomes of melanocytes
• Then the melanosomes are transferred from the
  melanocyte to a group of keratinocytes called the
  epidermal melanin unit
• Variations in skin color is related to the number
  of melanosomes, the degree of melanization, and
  the distribution of the epidermal melanin unit

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Pigmentary Demarcation Lines

• Can be divided into five categories
• Group A- lines along the outer upper arms with
  variable extension across the chest
• Group B-lines along the posteromedial aspect of
  the lower limb
• Group C-Paired median or paramedian lines on the
  chest, with midline abdominal extension
• Group D-medial, over the spine
• Group E-bilaterally symmetrical, obliquely
  oriented, hypopigmented macules on the chest

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Pigmentary Demarcation Lines

• More than 70 of blacks have one or more lines
• These are much less common in whites
• Type B lines often appear for the first time
  during pregnancy

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Normal Pigmentation

• Normal skin pigmentation is influenced by
• -the degree of vascularity
• -the amount location of melanin
• -the presence of carotene
• -the thickness of the horny layer

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Melanin Production

• The amount produced is dependent on
• -genetics
• -the amount and the wavelengths of ultraviolet
  light received
• -the amount of melanocyte-stimulating
  hormone(MSH) secreted
• - the effect of melanoccytestimulatingg
  chemicals like furocoumarins (psoralens)

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Hemosiderin Hyperpigmnetation

• Pigmentation due to deposits of hemosiderin
  occurs in
• -purpura
• -hemochromatosis
• -hemorrhagic diseases
• -stasis ulcers
• difficult to distinguish from postinflammatory
  dermal melanosis clinically

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Postinflammatory Hyperpigmentation

• Any inflammatory condition can cause either
  hypopigmentation or hyperpigmentation
• Also may be a complication of chemical peels,
  dermabrasion, laser therapy, or liposuction
• Histologically, there is melanin in the upper
  dermis and around upper dermal vessels, located
  primarily in macrophages (melanophages)

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Postinflammatory hyperpigmenation

• Postinflammatory hyperpigmentation following
  resolution of lymphocytoma cutis on the cheek of
  a black child

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Industrial Hyperpigmentation

• Occurs in coal miners, anthracene workers, pitch
  workers, etc
• Pigmentation of the face may occur from the
  incorporation in cosmetics of derivatives of coal
  tar, petrolatum, or picric acid, mercury, lead,
  bismuth, or furocoumarins (psoralens)

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Systemic Diseases

• Syphilis, malaria, pellagra, and diabetes
• Addisons disease- diffuse melanosis pronounced
  in the axillae and palmar creases, and nipples
  and genitals, and buccal mucosa
• Diabetes produces diffuse bronzing of the skin
• patients with virilizing adrenal tumors
  usually develop hyperpigmentation and
  hypertrichosis

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Systemic Diseases

• Nelsons syndrome (a pituitary MSH-producing
  tumor)
• Pheochromocytoma
• Hemochromatosis
• Amyloidosis
• Scurvy
• Pregnancy
• Menopause
• Porphyria cutanea tarda

• Vitamin B12 deficiency
• Kwashiorkor
• Vitamin A deficiency
• Primary biliary cirrhosis (triad
  hyperpigmentation, pruritis, xanthomas)

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Hemochromatosis

• Characterized by
• Gray-brown mucocutaneous hyperpigmentation
• Diabetes mellitus
• hepatomegaly

• Usually are present
• Cirrhoisis
• Hypogonadism
• Liver cirrhosis

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Hemochromatosis

• Skin pigmentaion is usually generalized
• But, more pronounced on face, extensor aspect of
  the forearms, backs of the hands, and the
  geniocrural area
• Iron is deposited in the skin
• Iron is present as granules around blood vessels
  and sweat glands and within macrophages

• The actual pigmentation is caused by increased
  basal-layer melanin
• Mucous memebranes are pigmented in up to 20 of
  patients
• Koilonychia is present in 50
• Localized ichthyosis in 40
• Alopecia is common

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Hemochromatosis-tx

• Phlebotomy until satisfactory iron levels are
  found
• Extracorporeal chelation has also been used
  successfully
• Associated DM requires medical tx
• Long-term complications are cirrhosis and then
  hepatomas

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Melasma

• Brown patches, sharply demarcated, typically on
  the malar prominences and forehead
• The three clinical patterns are centrofacial,
  malar, mandibular
• Increased pigment may simultaneously occur around
  the nipples and external genitalia

• Tends to affect the darker-complected
• It may also be found on the forearms
• Occurs at pregnancy and at menopause
• It may also be seen in ovarian disorders and
  other endocrine disorders
• Most frequently 90 of the time seen in women,
  10 in men

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Melasma

• Tx- avoid sunlight, and a complete sun block with
  broad-spectrum UVA coverage should be used daily
• Kligmans formula (Triluma)
• gt then 4 hydroquinone may be needed
• Side effects of this is ochronosis and satellite
  pigmentation
• Jessners solution, glycolic acid peels,azelaic
  acid, kojic acid, and cystamine and buthionine
  sulfoximine are other options

• Strong association with the use of birth control
  pills or dilantin
• Discontinuing the contraceptives rarely clears
  the pigmentation, and it may last for years after
  discontinuing them.
• Melasma of pregnancy usually clears within a few
  months of delivery

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Melasma
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Melasma
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Melasma
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Acromelanosis Progressiva

• AKA acropigmentation
• A progressive pigmentary disorder first described
  in a Japanese infant
• Characterized by diffuse black pigmentation on
  the dorsum of all the fingers and toes
• Pigmentation became progressively more widespread
  and more pigmented

• By age 4 or 5 the perineum, extremities, and
  areas of the head and neck were involved
• Epileptiform seizures occurred
• History revealed consanguinity

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Pigmented Anomalies of the Extremities

• Acropigmentation of Dohi
• Found to affect individuals from Europe, India,
  Caribbean
• First described in Japan in 12 patients
• AKA dyschromatosis symmetrica hereditaria or
  symmetrical dyschromatosis of the extremities

• Patients develop progressive pigmented
  depigmented macules
• Often mixed in is a reticulate pattern
• Many believe this to be a variation of
  acropigmentation of Kitamura

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Reticular Pigmented Anomaly of the Flexures

• It begins age 20 to 30 yrs and progresses
  gradually
• Unknown etiology
• AD with variable penetrance and expressivity, and
  delayed onset

• Many authors believe it is a spectrum of
  reticulate acropigmentation of Kitamura
• Another manifestation of this disorder is
  familial-rocacea-like dermatitis with warty
  keratotic plaques on the trunk and limbs
• There is no treatment

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• Reticular pigmented anomaly of the flexures
• J. B. Howell and R. G. Freeman
• Reticular pigmented anomaly of the flexures
  (Dowling-Degos' anomaly) is a rare, benign, new
  genodermatosis that has recently evolved from
  independent observations and studies by several
  dermatologists. Because of its favorable
  prognosis, differentiation of this benign
  disorder from acanthosis nigricans, a cutaneous
  marker of possible or existing internal malignant
  disease, is highly important. Careful clinical
  appraisal of the eruption in correlation with the
  characteristic microscopic features makes the
  diagnosis simple and straightforward.

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Histology

• Distinctive elongation, tufting, and deep
  hyperpigmentation of therete ridges, with
  protrusion of similar tufts even from the sides
  of the follicles

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Reticulate Acropigmentation of Kitamura

• AD
• Characterized by linear palmar pits and pigmented
  macules 1-4 mm in diameter on the volar and
  dorsal aspects of the hands and feet

• One report of a pt with bony abnormalities
  consisting of absence of terminal phalanges of
  the second, third, and fourth toes
• Some tx success has been reported using axelaic
  acid ointment

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Dermatopathia Pigmentosa Reticularis

• Consists of a triad of generalized reticulate
  hyperpigmentation, noncicatricial alopecia, and
  onychodystrophy
• Other associations adermatoglyphia, hypohidrosis
  or hyperhidrosis, palmoplantar hyperkeratosis,
  and nonscarring blisters on dorsa of hands and
  feet.

• An autosomal dominant inheritance pattern has
  been reported.

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Dermatopathia Pigmentosa Reticularis
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Transient Neonatal Pustular Melanosis

• Histologically, there are intracorneal or
  subcorneal aggregates of predominantly
  neutrophils, but eosinophils may also be found
• Dermal inflammation is composed of an admixture
  of neuts and eos
• Differential dx ETN, neonatal acne,
  acropustulosis of infancy

• Infants develop 2- 3mm macules, pustules, and
  ruptured pustules at birth, predominantly
  involving the face
• Pigmentation may last for weeks or months after
  the pustules are healed

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Transient Pustular Neonatal Melanosis
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Transient Neonatal Pustular Melanosis
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Peutz-Jeghers

• Associated polyposis involves the small intestine
  preferencely
• But, hamartomatous polyps of the stomach and
  colon may occur
• Symptoms of hamhartomas of the small intestine
  may cause repeated bouts of abdominal pain and
  vomiting, and intussusception

• Characterized by hyperpigmented macules on the
  lips and oral mucosa and polyposis of the small
  intestine
• Dark brown or black macules appear typically on
  the lips, especially the lower lip, in infancy or
  childhood
• Similar lesions may appear on buccal mucosa,
  tongue, gingiva, and genital mucosa

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Peutz-Jeghers syndrome

• Lip lentigenes in an adolescent with
  Peutz-Jeghers syndrome

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P-J syndrome
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Pathology
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Reihls Melanosis

• Photosensitivity, phototoxic dermatitis
• Begins with pruritis, erythema, and pigmentation,
  gradually spreads, then becomes stationary
• Melanosis occurs mostly in women and develops
  over months

• Characteristic feature is spotty light to dark
  brown pigmentation
• Most intense on the forehead, malar regions,
  behind the ears, on the sides of the neck, on
  other sun-exposed areas
• Also circumscribed telangiectasia and temporary
  hyperemia

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Tar Melanosis

• An occupational dermatosis occurring among tar
  handlers after years of exposure
• Severe, widespread itching develops, followed by
  reticular pigmentation, telangiectases, and a
  shiny appearance of the skin
• There is a tendency for hyperhidrosis

• Small, dark, lichenoid, follicular papules become
  profuse on the extremities, namely the forearms
• Bullae are sometimes observed
• Represents a photosensitivity or phototoxicity
  induced by tar

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Universal Acquired Melanosis(Carbon Baby)

• Ruiz-Maldonado reported a case of a Mexican
  child, born white, who progressively became black
• Developed pigmentation of the palms, soles,
  mucous membranes

• EM showed a negroid pattern in the melanosomes of
  the epidermal melanocytes and keratinocytes
• Melanocytes were not increased in number

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Periorbital Hyperpigmentation

• 1.) Familial periorbital melanosis (AD)
• Usually involves all four eyelids, may extend to
  involve the eyebrows and cheeks

• 2.) Erythema dyschromicum perstans is a rare
  cause
• 3.) Familial dark circles around the eyes,
  frequently seen in individuals of Mediterranean
  ancestry

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Metallic Discolorations

• Pigmentation from deposition of fine metallic
  particles in the skin
• Metal may be carried to skin from the blood
  stream or may permeate into it from surface
  applications

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Argyria

• Local tx with a silver-containing product may
  produce argyria
• Examples conjunctivae, from eye drops a wound
  from sulfadiazine cream, earlobes from silver
  earings and from silver acupuncture needles
• Can also occur from occupational exposure,
  usually siversmiths
• In localized exposures, the appearance may be
  separated by many years from the exposure

• Localized or widespread slate-colored
  pigmentation
• Due to silver in the skin
• Most noticeable in parts exposed to sunlight
• Tissue silver may stimulate melanocytes
• Initially discoloration is hardly perceptible,
  having only a faint blue color, but a slate-gray
  color develops with time

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Histology

• Systemic and localized argria have the same
  features
• Normal appearing skin under low power
• Fine black granules in the basement zone of the
  sweat glands,blood vessel walls, d-e junction,
  and arrector pili muscles
• Unstained biopsy section by darkfield
  illumination demonstrates silver granules
  outlining basement membrane of the epidermis and
  the eccrine sweat glands

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Bismuth

• Rarely associated with deposition of metallic
  particles in gums when used IM or orally
• Also known as the bismuth line
• Presence of stomatitis or peridontitis increased
  the risk
• Generalized cutaneous discoloration, in addition
  to oral mucous membrane and conjunctival
  pigmentation resembling argyria has occurred but
  has not be reported in the last 50 years

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Lead

• Chronic lead poisoning can produce a lead hue
  with lividity and pallor
• Deposit of lead in the gums may occur and is
  known as the lead line

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Iron

• In the past, soluble iron compounds were used in
  the treatment of allergic contact dermatitides
• In eroded areas iron was sometimes deposited in
  the skin, like a tattoo
• Use of Monsels solution can produce similar
  tattooing

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Gold

• Chrysiasis may be induced by parenteral
  administration of gold salts, usually for the
  treatment of rheumatoid arthritis
• More commonly recognized in white patients
• A mauve, blue, or slate/gray pigmentation
  develops initially on the eyelids, spreading to
  the face, dorsal hands, and other areas
• Severity is related to the total dose received,
  rare lt a dose of 20 mg/kg of elemental gold

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Mercury

• Mercurial pigmentation in the skin is rare,
  especially since the use of mercurials has been
  strictly controlled
• Most common presentation is subcutaneous nodules
  that result from accidental implantation of
  elemental mercury from a thermometer into skin

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Canthaxanthin

• Orange-red pigment canthaxanthin is present in
  many plants ( notably algae and mushrooms) and in
  bacteria. Crustaceans, sea trout, and feathers
• When ingested for the purpose of simulating a
  tan, its deposition in the panniculus imparts a
  golden orange hue to the skin
• Stools become brick red and the plasma orange,
  and golden deposits appear in the retina

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Dye Discoloration

• Blue hands from accidental dyeing were reported
  by Albert in 1976
• A mans hands were dyed as a result of warming
  them in his armpits while wearing a new blue
  flannel shirt
• The dye was insoluble in water, but soluble in
  sweat

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Rubeosis

• A rosy coloration of the face occurring in young
  people with uncontrolled diabetes mellitus
• May be associated with xanthochromia to produce a
  peaches and cream complexion

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Vitiligo

• Usually begins in childhood or young adulthood
• 50 of cases begin before age 20
• Prevalence ranges from 0.5 to 1
• Females are disproportionately represented among
  patients seeking medical care, it is not known if
  it is actually more common in females or simply
  because they more often bring it to their
  physicians attention

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Clinical Features

• An acquired pigmentary anomaly of the skin
• Manifested by depigmented white patches
  surrounded by a normal or a hyperpigmented border
• There may be intermediate tan zones or lesions ,
  halfway between the normal skin color and
  depigmentaton-so-called trichrome vitiligo
• Hairs in vitiliginous areas usually become white
  also

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Types

• Localized or focal(including segmental)
• Generalized
• Universal
• Acrofacial

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Vitiligo

• Generalized is the most common
• Involvement is symmetrical
• Most commonly involving the face, upper chest,
  dorsal aspects of the hands, axillae, and groin
• Tendency for skin around orifices to be affected
  (eyes,nose, mouth, ears, nipples, umbilicus,
  penis, vulva, anus)
• Lesions also favor areas of trauma (elbows and
  knees)

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Generalized Vitiligo

• Involvement of perineal and inguinal skin
• Note the distinct borders

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Acral Vitiligo
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Symmetric, Acral Vitiligo

• Left pre-PUVA treatment
• Rightsame pt shows perifollicular pattern of
  repigmentation during PUVA therapy

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Segmental Vitiligo

• Rapidly progressing segmental vitiligo

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Segmental Vitiligo

• Segmental vitiligo of the eyebrow and eyelashes

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Segmental Vitiligo

• Segmental vitiligo on the arm , neck, and chest
• Note areas of spontaneous follicular
  repigmentation
• Left upper back with partial spontaneous
  repigmentation

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Universal Vitiligo

• Applies to cases where the entire body surface is
  depigmented

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Acrofacial Vitiligo

• Type affecting the distal fingers and the facial
  orifices

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Childhood Vitiligo

• Shows an increase in segmental presentation
• More frequent autoimmune or endocrine anomalies
• High incidence of premature graying in females

• Poor response to PUVA therapy

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Vitiligo

• Completely depigmented oval ivory white areas
  with convex hyperpigmentated borders

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Vitiligo

• Vitiligo with depigmentation of the lips

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Chemical Depigmentation

• Chemical depigmentation due to a germicidal
  detergent
• Pts usually improve with discontinuation of the
  offending agent

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Pathogenesis

• Three possible mechanisms have been proposed as
  inducing vitiligo are autoimmunity, neurohumoral
  factors, and autocytotoxicity
• No mechanism has been conclusively proven

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Histology

• There is complete loss of melanocytes
• Usually there is no inflammatory component

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Differential

• Morphea
• Lichen sclerosis
• Pityriasis alba
• Tinea versicolor tertiary pinta

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Treatment

• Fair-skinned pts may manage their disease with
  sunblock
• Sun protection is mandatory in all pts with
  vitiligo because of the loss of protection from
  UV radiation in the depigmented skin
• Topical steroids may be useful on focal or
  limited lesions
• Mid to super high-potency steroids are often
  required on trunk and acral lesions with the
  strength tapered as the lesions respond

• Spontaneous repigmentation occurs in no more than
  15 to 25 of cases
• Response is slow
• PUVA may actually worsen the appearance initially
  by pigmenting surrounding skin
• Cover-up strategies(topical dyes, make-up,
  self-tanning creams)

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• If gt 50 of the body surface area is affected
  by vitiligo, the pt can consider depigmentation
• This tx is permanent
• Monobenzone 20 is applied BID for 3-6 months to
  residual pigmented areas
• Up to 10 months may be required
• One in six pts will experience acute dermatitis,
  usually confined to the still-pigmented areas

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Vitiligo

• Partial repigmentation of lesions of vitiligo on
  the leg of a 14-year-old child at the end of the
  summer of sun exposure

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Vitiligo

• Partial repigmenation of vitiligo following
  psorralen-ultraviolet light (PUVA) therapy

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Vitiligo

• Permanent repigmentation after 2 years of
  photochemotherapy (tripsoralen followed by
  sunlight exposure)

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Vogt-Koyanagi-Harada Syndrome

• Characterized by bilateral uveitis, symmetrical
  vitiligo, alopecia, white scalp hair, eyelashes
  and brows(poliosis, and dysacousia(diminished
  hearing)
• Occurs in thirties
• Initial or meningoencephalitic phase occurs with
  prodromata of fever, malaise, headache, nausea,
  and vomiting
• Also may have psychosis, paraplegia, hemiparesis,
  aphagia, and nuchal rididity
• Recovery is usually complete

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VKHS

• Second phase(ophthalmic-auditory stage) is
  characterized by uveitis, dreased visual acuity,
  photopobia, and decreased hearing(50)
• The convalescent phase begins 3weeks to 3 months
  after it begins to improve

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Alezzandrinis Syndrome

• Extremely rare syndrome characterized by a
  unilateral degenerative retinits
• This is followed several months later by
  ipsilateral vitiligo on the face and ipsilateral
  poliosis
• Deafness may also be present

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Alezzandrinis Syndrome
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Leukoderma

• Postinflammatory leukoderma may result from
  inflammatory dermatoses ie
• Pityriasis rosea, psoriasis, herpes zoster,
  secondary syphilis, and morphea, sarcoidosis,
  tinea versicolor, mycosis fungoides, scleroderma,
  and pityriasis lichenoides chronica, and leprosy
• Other causes burns, scars, postdermabrasion, and
  intralesioal steroid injections

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Leukoderma

• Postinflammatory hypopigmentation in a
  4-month-old black child with atopic dermatitis

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Leukoderma

• Postinflammatory hypopigmentation following
  resolution of guttate psoriasis

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Pityriasis alba

• Ill-defined hypopigmented oval patches are
  generally seen on the face, upper arms, neck, and
  shoulders of affected persons
• It can be differentiated from vitiligo by its
  fine adherent scale, partial hypopigmentation,
  and distribution

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Pityriasis alba

• White, slightly scaly patches with indistinct
  borders on a childs cheek

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Postinflammatory hypopigmentation
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Albinism

• A partial or complete congential absence of
  pigment in the skin, hair, and eyes
  (oculocutaneous albinism), or the eyes alone
  (ocular albinism)
• Cutaneous phenotype of the various forms is
  broad, but the ocular phenotype is reasonably
  constant in most forms
• The ocular phenotype includes decreased visual
  acuity, nystagmus, pale irides that
  transilluminate, hypopigmented fundi, hypoplastic
  foveae, and lack of stereopsis

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Albinism

• This pt has light skin, yellowish white hair, and
  a lack of pigmentation in nevi

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Oculocutaneous Albinism 1

• OCA 1 results from mutations in the tyrosinase
  gene
• Affected pts are homozygous for the mutant gene
  or are compound heterozygotes for different
  mutations in the tyrosinase gene
• AR
• Two forms 1) OCA 1A OCA 1B (indistinguishable
  at birth)
• OCA 1 is most severe with complete absence of
  tyrosinase activity and complete absence of
  melanin in the skin and eyes
• Visual acuity is decreased to 20/400
• OVA 1B tyrosinase activity is reduced but not
  absent. Pts may show increase in skin,hair, eye
  color with age and can tan

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OCA 1

• OCA 1B was originally called yellow mutant
  albinism
• Temperature sensitive OCA (OCA 1-TS) results
  from mutations in the tyrosinase gene that
  produce an enzyme with limited activity lt 35
  degrees C and no activity below this temp. pts
  have white hair, skin, andeyes at birth, at
  puberty dark hair develops in cooler acral areas

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• Topalbinism with white hair, pale skin, and
  translucent irides
• Bottomophthalmoscopic view of a pt with albinism
  demonstrates a pale fundus, poor macular
  development, and prominent choroidal vasculature

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Oculocutaneous Albinism 2

• Prevalence of 115,000
• Pts were named tyrosinase-positive albinos
• AR and mutations occur in the P gene
• P gene codes a membrane transport protein that
  is present in the melanosome membrane
• Cutaneous phenotype of OCA 2 pts is broad,
  ranging from nearly normal pigmentation to
  virtually no pigmentation
• Pigmentation increases with age, and visual
  acuity improves with age
• Prader-Willi and Angelman syndromes are caused by
  deletions in the P gene 1 of pts with these
  syndromes also have OCA 2

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Oculocutaneous Albinism 3

• AR-caused by mutations in the tyrosine-related
  protein 1 (TRP-1), located on chromosome 9
• OCA 3 has been described only in black pts and is
  characterized by light brown hair, light brown
  skin, blue/brown irrides, nystagmus, and
  decreased visual activity
• Brown rather than black melanin is formed

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Ocular Albinism

• There are multiple forms of ocular albinism
• OA 1 may be present with lighter than expected
  skin
• It is X-linked
• Female carriers have mud-splattered fundi
• Macromelanosomes are found in the skin, so skin
  bx may be a helpful tool
• Many cases of AR ocular albinism have been
  reclassified as OCA 1 or OCA 2

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Syndromes Associated with Albinism

• Chediak-Higashsi Syndrome
• Hermansky-Pudlak Syndrome
• Griscelli Syndrome(partial albinism with
  immunodeficiency)
• Elejalde Syndrome
• Cross-McKusick-Breen Syndrome
• Cuna Moon Children

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Classification of Oculocutaneous Albinism
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Selenium Deficiency

• Selenium deficiency in the setting of total
  parental nutrition can lead to pseudoalbinism
• Skin and hair pigmentation return to normal with
  supplementation

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Waardenburgs Syndrome

• Four genotypic variants exist
• Types 1 3 are caused by mutations in the PAX
  gene on chromosome 2
• Type 2 is caused by mutations in the MITF gene on
  chromosome 3, and type 4 due to mutations in the
  ENDRB gene on chromosome 13

• Pts have features of piebaldism, with white
  forelock, hypopigmentation, premature graying,
  synophrys, congenital deafness, a broad nasal
  root, and ocular changes including heterochromia
  irides
• Apparently, melanoblasts fail to reach the target
  sites during embryogenesis

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Piebaldism

• Rare, AD with variable phenotype, presenting at
  birth
• White forelock, patchy absence of skin
  pigmenation
• Depigmented lesions are static and occur on the
  anterior and posteroir trunk, mid upper arm to
  wrist, mid-thigh to mid-calf, and shins
• A characteristic feature is the presence of
  hyperpigmented macules within the areas of lack
  of pigmentation and on normal skin

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Piebaldism
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Piebaldism

• Segmental white patch on the neck with a tuft of
  white hair present from birth

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Piebaldism

• White forelock and patch of unpigmented skin in a
  young girl with piebaldism

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Piebladism

• The white forelock arises from a triangular or
  diamond-shaped midline white macule on the
  frontal scalp or forehead
• The medial portions of the eyebrows, and
  eyelashes may be white
• Histologically, melanocytes are completely absent
  in the white macules
• Etiology is a mutation in the c-kit protooncogene
• Phenotypic differences seen in families is caused
  by different locations of mutations in the gene
• The white lesions may respond to surgical excision

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Idiopathic Guttate Hypomelanosis

• AKA leukopathica symmetrica progressiva
• Very common aquired disorder affecting women more
  frequently than men
• Usually occurs after age 40
• Lesions occur on the shins and forearms are
  small (6 or 8mm), rarely become very numerous ( a
  dozen or two at most), and never occur on the
  face or trunk
• Lesions are irregularly shaped and very sharply
  defined, like depigmented ephelides, and are only
  of cosmetic significance

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Idiopathic Guttate Hypomelanosis