A 55-year-old man presents with progressive orange-red scaly plaques merging into generalized erythroderma, but with distinct patches of normal skin ('islands of sparing') interspersed. Follicular keratotic papules are noted on the dorsal fingers. The most characteristic finding is:
- A Wickham striae
- B Auspitz sign
- C Islands of sparing ✓
- D Herald patch
Correct answer: C. Islands of sparing
Explanation
Islands of sparing are pathognomonic of pityriasis rubra pilaris and distinguish it from other causes of erythroderma. Auspitz sign is seen in psoriasis. Wickham striae are characteristic of lichen planus. Herald patch is the initial lesion of pityriasis rosea.
Reference: Bolognia's Dermatology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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