Melanocytes and Disorders of Pigmentation Flashcards
Melanocytes:
What are they derived from? What is their function?
derived from neural crest and produce pigment (melanin)
- They are dendritic cells with dendrites that extend to multiple keratinocytes facilitating melanin transfer via melanosomes
- Epidermal-melanin unit:
- melanocyte and its surrounding keratinocytes
- roughly 1:10 (varies by location and sun-damage)
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What is an epidermal-melanin unit?
melanocyte and its surrounding keratinocytes
roughly 1:10 (varies by location and sun-damage)
Where are melanocytes located?
the basale layer, with dendrites branching up and out
What are racial differences in skin color determined by?
characteristics of melanosomes. not size or number or melanocytes!
the size, number and distribution of the melanosomes. melanosomes are the pigment granules within a keratincyte
What is pigmentation and what is it dependent on?
melanocyte number and density does not vary by race
pigementation dependent on the size, number, and density of melanosomes (pigment granules in keratinocytes)
what is the relationship between melanocytes, melanosomes and melanin
melanocytes (cells) transfers melanosomes (granules) that are filled with melanin (pigment)
What is:
hyperpigmentation
hypopigmentation
depigmentation
- hyperpigmentation: darker than surrounding of normal color; increased pigment
- hypopigmentation: lighter than surrounding skin; decreased pigment
- Depigmentation: white; no pigment
to differentiate between white and light areas for hypo vs. depigmentation
WHat is this? hyper, hypo or de
hyperpigmentation
what is this? hyper.,hypo or de
hypo
How do you get tuberous sclerosis? What does it causes?
- majrity (2/3) new spontaneous mutations, autosomal dominant genetic disorder
- 1/5800-1/10,000 births
- TSC1 (hamartin), TSC2 (tuberin) mutation
- causes non-malignant tumors of the brain, eyes, heart, kidney, skin, lungs
what 4 things do you usually have if you have tuberous sclerosis?
- hypopigmented macules (3 or more)
- Angiofirbomas and fibrous plaque
- shagreen patch
- periungual fibromas
What are these?
angiofibromas and fibrous plaque
what are these
shagreen patch
what are these
periungal fibromas
what does this little girl have?
depigmentation
what is oculocutaneous albinism?
- genetic disorder (autosomal dominant or recessive)
- defect in tyrosinase or related proteins leading to impaired melanin production
- white to yellow/red hair with light to white skin depending on type of albinism
- high risk of skin cancer due to lack of melanin
What is this?
ephelides (freckles)
occur in sun-exposed areas of bdy
they darker with sun exposure. markers of UV induced damage and are a risk factor for melanoma
What is this?
cafe au lait macules
- well circumscribed uniformly light to dark brown macules or papules which typicall occur in infancy or early childhood
What are these?
What are these
axillary freckling
What are these?
neurofibromas
what are these?
plexiform neurofibromas
What is solar lentigo?
“sun spots” “liver spots”
sun-exposed ares, bigger than ephelids
What is dermal melanocytosis?
aka “Mongolian spot”
- deper pigament (in lower dermis) creates the bluish color
- lumbrosacral most common: fading over time typical in this location
**often confused with child abuse or ecchymoses
what are melanocytic nevi
acquired moles that are probably benign
- subtypes have more histological significance than clinical (refer to location og melanocytic nests)
- junctional-DEJ
- compound- DEJ and in the dermis
- intradermal- in the dermis
Congenital melanocyte nevi
- larger than acquired nevi, range in size from 1cm to greater than 20cm at birth
- risk of melanoma
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What is the significance of having a large congenital myelanocytic nevi?
- higher riskfor melanoma than smaller CMV
- risk for neurocutaneous melanosis
- leptomeningeal melanosis or even melanoma
