19.4 - Disorders of pigmentation and melanocytes

Question 1

melanocytes are responsible for skin pigmentation and are present in the __________ layer of the epidermis

Answer 1

basal

Question 2

melanocytes are derived from what germ layer?**

Answer 2

neural crest

Question 3

how does pigmentation occur?

Answer 3

• melanin synthesized in melanosomes using tyrosine as a precursor molecule
• melanosomes are passed to keratinocytes

Question 4

vitiligo is due to autoimmune destruction of ___________ (cell type)

Answer 4

melanocytes

Question 5

albinism is (usually) due to a defect in what enzyme?

Answer 5

tyrosinase

Question 6

freckles are also known as __________ and are due to increased number of ___________

Answer 6

• ephelis

- melanosomes (NOT melanocytes)

Question 7

what is the mask-like hyperpigmentation of the cheeks often seen with pregnancy and oral contraceptives?

Answer 7

melasma

Question 8

what is the most important prognostic factor in predicting metastasis for melanoma?

Answer 8

depth of extension (Breslow thickness)

Question 9

what is a compound nevus?

Answer 9

acquired nevus that grows by extension into dermis

Question 10

what is the most common type of nevus in adults? children?

Answer 10

• adults: intradermal

- children: junctional