ABD Pigmentary Disorders

Question 1

Which autoantigen is most commonly targeted by autoantibodies in generalized vitiligo?

Accepted Answer

Tyrosinase and tyrosinase-related proteins (TRP-1, TRP-2)

Answer

Vitiligo involves autoimmune destruction of melanocytes, with autoantibodies most commonly targeting tyrosinase and tyrosinase-related proteins TRP-1 and TRP-2.

Question 2

Under Wood's lamp examination, vitiligo-affected skin characteristically shows:

Accepted Answer

Bright blue-white (chalk-white) fluorescence accentuating depigmentation

Answer

Vitiligo shows striking bright blue-white fluorescence under Wood's lamp due to complete melanin loss, which accentuates the depigmented patches and helps reveal subclinical lesions.

Question 3

Kligman's formula, the gold standard for melasma treatment, consists of which combination?

Accepted Answer

Tretinoin + hydroquinone + low-potency topical corticosteroid

Answer

Kligman's formula combines tretinoin (enhances penetration and turnover), hydroquinone (inhibits tyrosinase), and a low-potency corticosteroid (reduces irritation), targeting melasma through multiple mechanisms.

Question 4

Post-inflammatory hyperpigmentation (PIH) is more persistent in darker skin types primarily because:

Accepted Answer

Both epidermal melanin deposition and dermal melanophage formation occur

Answer

PIH involves both epidermal hyperpigmentation from activated melanocytes and dermal melanophages from melanin incontinence; the dermal component is difficult to treat and accounts for prolonged PIH in darker phototypes.

Question 5

Oculocutaneous albinism type 1A (OCA1A) results from mutations in which gene, producing what enzymatic defect?

Accepted Answer

TYR gene; complete absence of tyrosinase enzyme activity

Answer

OCA1A is caused by loss-of-function mutations in the TYR gene encoding tyrosinase, the rate-limiting enzyme in melanin biosynthesis, resulting in complete absence of melanin production.

American Board of Dermatology (ABD) Practice Test

American Board of Dermatology (ABD) Practice Test

ABD Pigmentary Disorders