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

Desmoglein 3

Answer

BP180 (type XVII collagen)

Answer

Antinuclear antigens (ANA)

Question 2

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

Accepted Answer

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

Answer

Yellow-green fluorescence

Answer

Coral-pink fluorescence

Answer

Orange-red folliculocentric fluorescence

Question 3

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

Accepted Answer

Tretinoin + hydroquinone + low-potency topical corticosteroid

Answer

Azelaic acid + kojic acid + benzoyl peroxide

Answer

Salicylic acid + niacinamide + retinol

Answer

Glycolic acid + vitamin C + broad-spectrum sunscreen alone

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

Melanocytes are more numerous in darker skin

Answer

Keratinocyte turnover is slower

Answer

Mast cell density is higher in darker skin

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

OCA2 gene; defective P-protein melanosomal transporter

Answer

TYRP1 gene; defective tyrosinase-related protein 1

Answer

MC1R gene; defective melanocortin-1 receptor signaling

Question 6

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

Accepted Answer

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

Answer

Bilateral periorbital and malar regions symmetrically

Answer

Diffuse facial involvement with ipsilateral scalp extension

Answer

Bilateral malar distribution sparing periorbital skin

Question 7

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

Accepted Answer

Incomplete hypopigmentation with fine scale and association with atopic dermatitis

Answer

Lesions appearing on the face

Answer

Response to topical calcineurin inhibitors

Answer

Worsening with ultraviolet light exposure