Melanocyte disorders

Question 1

Melanocytes

Answer 1

Derived from neural crest

Produce pigment

Dendritic cell (dendrites extend to multiple keratinocytes facilitating melanin transfer)

Epidermal melanin unit: melanocyte and keratinocytes with which it interacts (roughly 1:10)

Question 2

Pigmentation

Answer 2

melanocyte number and density DO NOT vary by race

its the size, nember, and density of MELANOSOMES (pigment granules in keratinocytes)

Question 3

Pigmentation

Answer 3

Hyperpigmentation-darker than surroungdin
Hypo-lighter
De pigmentation: white, no pigment

Question 4

tuberous sclerosis

Answer 4

Autosomal dominant genetic disorder

Cauases non malignant tumors of the brain, eyes, heart, kidney, skin, and lungs

1/5800 to 1/10000
TSC1 (hamartin), TSC2 (tuberin) mutations

Majority is new spontaneous mutations

3 or more hypopigmented macules

Question 5

Vitiligo

Answer 5

T cell mediated autoimmune disorder, destruction of melanocytes with subsequent development of depigmented patches

Typically acquired (not present at birth)

Progressive course is typical

Hair in affected area usually is white (poliosis)

Question 6

Oculocutaneous Albinism

Answer 6

Genetic disorder (autosomal dominant or recessive)

Defect in Tyrosinase or related proteins

Impaired melanin production

White yellow/red hair white skin depending on type of albinism

Question 7

Types of brown spots

Answer 7

Ephelides (freckles)
Cafe au lait macules
Solar lentigo/lentigines (liver spots)
Melanocytic nevi (acquired)
Congenital melanocytic nevi

Question 8

Neurofibromatosis 1

Answer 8

AKA Von Recklinghausens disease
Autosomal dominant
Mutations in neurofibromin
Up to 50% spontanteous mutations
1/3000 births

Skin presentation: Cafe au lait pigmentation

Axillary/inguinal freckling

Neuro fibromas

Question 9

Solar lentigo

Answer 9

Age or liver spots

Sun exposed areas

Bigger than ephelids

Question 10

Dermal melanocytosis

Answer 10

aka Mongolian spot

Blue butt

Deeper pigment in lower dermis creates bluish color

Lumbosacral region

Question 11

Melanocytic Nevi (acquired)

Answer 11

Subtypes have more histologic significance than clinical

Compound, Junctional, Intradermal

Risk of malignant transformation

A-asymmetry, B-border irregularity/blurred border, c-color heterogeneity, D- diameter greater than 6mm, E-evolution/change

Question 12

Congenital melanocytic nevus

Answer 12

CMN

Large/Giant CMN: higher risk for melanoma than smaller CMN, Risk for neurocutaneous melanosis

Leptomeningeal melanosis or even melanoma