Pityriasis rubra pilaris (PRP) Type I (classic adult) is distinguished from psoriasis by which clinical feature?

• A Presence of Wickham striae on lesions
• B Auspitz sign and silvery scaling
• C Koebner phenomenon and nail pitting
• D Islands of normal skin ('nappes claires') within areas of erythroderma ✓

Explanation

Classic adult PRP (Type I) characteristically shows islands of spared normal skin within areas of salmon-orange erythroderma — 'nappes claires' (French: clear patches). This 'skip area' pattern is pathognomonic for PRP and helps distinguish it from psoriatic erythroderma which tends to be confluent. Other features of PRP: follicular keratotic papules on the dorsal fingers ('nutmeg grater' feel), palmoplantar keratoderma (waxy yellow 'sandal'), and cephalocaudal spread. Auspitz sign, nail pitting, and Wickham striae are features of psoriasis and lichen planus respectively.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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