19.4: Disorders of pigmentation and Melanocytes Flashcards
What are the organelles in which melanin is produced in melanocytes?
melanosomes
True or false: keratinocyte produce the melanin found within them
False- melanocytes produce the pigment, then ship it off to local keratinocytes
Which layer of the epidermis are melanocytes found in?
Basal layer
Melanocytes are derived from what type of cells in development?
Neural crest cells
What is the precursor amino acid that is needed to produce melanin? What is the enzyme that converts it?
- Tyrosine
- Tyrosinase
What, generally, is vitiligo?
Autoimmune destruction of the melanocytes, resulting in a localized loss of skin pigmentation
How does Vitiligo present?
Localized areas of a lack of skin pigmentation
What is the enzyme that is usually deficient in albinism?
Tyrosinase
What is the concern with albinism, besides cosmetic / psychological effects?
Increased risk of skin cancer
What causes a freckle to darken with sunlight?
Increased numbers of melanosomes (NOT melanocytes)
What is melasma?
Mask-like hyperpigmentation of the cheeks, associated with pregnancy and oral contraceptives
What is a nevus?
Benign neoplasm of melanocytes (“mole”)
Do congenital or acquired nevi usually have hair associated with them?
Congenital
Will there be hair in melanoma?
No–only melanocytes
What are junctional nevi, and what age group are they usually found in?
melanocytes that progress through the epidermis, all the way to the dermal-epidermal junction
What is a compound nevus?
Nevus with melanocytes extending into the dermis
What is an intradermal nevus? In what age range is this common in?
Nevus that is fully comprised of dermal cells, without a junctional component
What is melanoma?
Malignant proliferation of melanocytes
What skin cancer is the most lethal?
Melanoma
What is dysplastic nevus syndrome? What is the inheritance pattern?
AD disorder, characterized by formation of dysplastic nevi that may progress to melanoma
What are the ABCDEs of melanoma?
- Asymmetry
- Borders (irregular)
- Color (not uniform)
- Diameter more than 6 mm
- Evolution
A diameter greater than how many mm for a nevus is concerning for melanoma?
6mm
What are the two growth phases of melanoma?
- Radial growth along dermal/epidermal junction
- Vertical growth
What is the key risk factor for the development of metastases with melanocytes?
Vertical depth
What is lentigo malignant melanoma? Prognosis?
“lentiginous proliferation of melanocytes–meaning along the dermal - epidermal border
-Good prognosis
What is the superficial spreading subtype of melanoma? Prognosis?
- Melanoma with dominant early radial phase
- Good prognosis
What is the nodular form of melanoma? Prognosis?
- Melanoma with a vertical growth phase that begins early
- Poorer prognosis
What is acral lentiginous melanoma? Where on the body does it arise?
-Melanoma that arises on the palms or soles, often in dark skinned individuals
Which subtype of melanoma is not related to UV light exposure?
Acral lentiginous
What ethnicity is acral lentiginous melanoma more common in?
Dark-skinned individuals
