091714 melanocytes Flashcards
what types of cells are melanocytes?
dendritic cells with dendrites extending to multiple keratinocytes to facilitate melanosome transfer
what is pigmentation of skin dependent on?
size, number and density of melanosomes (pigment granules in keratinocytes)
Wood’s light
used to differentiate light from white areas of skin
tuberous sclerosis
autosomal dominant genetic disorder
causes non malignant tumors of brain, eyes, heart, kidney, skin, lungs
TSC1 (hamartin) and TSC2 (tuberin) mutations
vitiligo
autoimmune disorder
destruction of melanocytes and depigmented patches
often symmetric involvement
oculocutaneous albinism
inherited genetic disorder
absence or marked reduction of pigment in skin, hair, eyes
what is the pathogenesis of oculocutaneous albinism
defect in melanin production
what are oculocutaneous albinism pts at risk for
skin cancer b/c melanin plays protective role against photodamage
ephelides
freckles
what helps differentiate ephelides from other pigmented lesions?
they darken w sun exposure
cafe au lai macules
well circumscribed
uniformly light to dark brown macules or patches
not uncommon to have a few
multiple ones are rare though
solar lentigines
tan to dark brown or black macule due to UV irradiation
in contrast to ephelides, these are seen later in life and often bigger (5-15 mm)
occur in sites of sun exposure. may darken w/ sun exposure
dermal melanocytosis
blue-gray patches over lumbosacral region of infants w/ darker skin types
historically referred to as Mongolian spots
pigment usually fades w/ age
tend to be larger patches
what are some genetic diseases associated w/ pigmented or hypopigmented lesions?
neurofibromatosis type 1
tuberous sclerosis
neurofibromatosis type 1 is caused by mutations in what gene
NF1 gene enconding neurofibromin
what do pts w/ neurofibromatosis type 1 have on their skin?
multiple cafe au lait macules starting in childhood
axillary and inguinal freckling
with time, neurofibromas can develop in skin–look like soft or rubbery papules
plexiform neurofibromas-larger plaques that have a bag of worms feel
tuberous sclerosis results in
benign tumor formation in multple organ systems
tuberous sclerosis is caused by mutations in
TSC1 and TSC2, encoding hamartin and tuberin
skin involvement of tuberous sclerosis
facial angiofibromas–telangiectatic papules that develop on the central face
periungual fibromas (similar lesions found along nail folds)
hypomelanotic macules and patches (ash leaf macules) can be present in early childhood
