A 32-year-old man presents with well-demarcated erythematous plaques covered by thick silvery-white scales on his elbows and knees for the past 8 months. On scraping the scale, a characteristic bleeding point is observed. Which of the following best describes the complete sequence of signs elicited during this test?

• A Candle grease sign → Auspitz sign → Grattage sign
• B Auspitz sign → Grattage sign → Last membrane sign
• C Last membrane sign → Candle grease sign → Auspitz sign
• D Grattage sign → Last membrane sign → Auspitz sign ✓

Explanation

The Grattage test in psoriasis proceeds in a stepwise fashion: initial scraping produces a candle-grease phenomenon (heaping of silvery scales), continued scraping reveals the last shiny membrane (Bulkley's membrane — representing the thin suprapapillary epidermis), and further removal of that membrane exposes the dilated dermal papillary capillaries, producing punctate bleeding known as Auspitz sign. The correct sequence is Grattage sign → Last (Bulkley's) membrane sign → Auspitz sign. This triad is pathognomonic of psoriasis vulgaris.

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

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