Pigmentary Disorders Flashcards

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

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

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

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

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

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.

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

Answer: Tretinoin + hydroquinone + low-potency topical corticosteroid

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

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

Answer: Both epidermal melanin deposition and dermal melanophage formation occur

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.

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

Answer: TYR gene; complete absence of tyrosinase enzyme activity

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.

Nevus of Ota (oculodermal melanocytosis) is classically distributed along which anatomical territory?

Answer: Unilateral distribution along the ophthalmic and maxillary divisions of the trigeminal nerve

Nevus of Ota presents as unilateral bluish-gray dermal melanocytosis in the distribution of the first (ophthalmic, V1) and second (maxillary, V2) divisions of the trigeminal nerve, often involving the ipsilateral sclera.

Which feature best distinguishes pityriasis alba from vitiligo in a child with facial hypopigmented patches?

Answer: Incomplete hypopigmentation with fine scale and association with atopic dermatitis

Pityriasis alba shows incomplete hypopigmentation (not total depigmentation), has subtle fine scale, and occurs in the context of atopic dermatitis, whereas vitiligo shows complete melanin loss without scale.