Dermatology Pigmentation Disorders Flashcards
What is the difference between vitiligo and albinism?
Vitiligo is LOCALIZED loss of skin pigmentation due to ai destruction of melanocytes while Albinism is a congenital lack of pigmentation due to tyrosinase enzyme defect which impairs melanin production. May involve eyes or both eyes and skin. Albinism has increased risk of skin cancers due to reduced UVB protection (squamous, basal, melanoma).
What is the role of melanocytes? What is their embryo logical origin? What is their function?
Melanocytes are responsible for skin pigmentation and are present in the BASAL layer of the epidermis. Derived from NC. Synthesised melamine from tyrosine in melanosomes and pass melanosomes to keratinocytes.
What is ephelis and what causes it?
Freckles that are small, tan to brown macules that darken with exposure to sunlight. Due to increased number of melanosomes not melanocytes.
Patient presents with hyper pigmentation of the cheeks. What is it and what caused it?
MELASMA which is a mask like hyper-pigmentation of the skin commonly associated with pregnancy and OCTC.
A Native American patient with albinism comes to your derm clinic concerned with a mole like growth on his left thigh. What could the mole be? What risk factors cause it? How would you characterize the mole?
Pt is right to be concerned becasue he might have MELANOMA which is a malignant neoplasm of melanocytes and most common cause of death from skin cancer. Risk factors are UVB induced DNA damage, and include exposure to sunlight, albinism or XP. dysplastic Nevus syndrome which is AD and may progress to formation of dysplastic mole. Qualified by ABCD WITH Asymmetry, Irregular Borders, a on uniform Color and Diameter > 6 mm.
What are the two growth phases of melanoma and what are some of the variants?
Radial growth along epidermis and superficial dermis with low risk for metastasis. Vertical growth into the deep dermis with increased risk for metastasis and increases with depth of extension. Superficial spreading and Lentigo maligna melanoma have radial growth and good prognosis. Nodular has early vertical growth and poor prognosis. Acral lentiginous arises on the palms or soles and often in dark skinned individuals and not related to UV light exposure.
A 3 yo pt presented with a small 3 mm raised bump on his skin. Examination showed that it has sharp borders, color was evenly distributed. What is the cause of this mass? Is this congenital or acquired? How does it progress?
This is a NEVUS which is a benign neoplasm of melanocytes. Congential versions associated with hair. Acquired version arises later in life and begins as nests of melanocytes at dermal epidermal junction (junctional nevus) and grows by extension into the dermis (compound NEVUS) and junctional component is eventually lost leading to intra dermal NEVUS.
What is the most common mole in children ? Adults?
Most common in children is junctional NEVUS and in adults in intra dermal NEVUS.
