A patient with psoriasis presents with yellow-brown discoloration of the nail plate proximally, with the nail separating from the nail bed distally, and multiple pits on the nail surface. The yellow-brown area has a distinct border. What is the yellow-brown area called?
- A Oil drop sign (salmon patch) ✓
- B Leukonychia
- C Subungual hyperkeratosis
- D Beau's lines
Correct answer: A. Oil drop sign (salmon patch)
Explanation
The oil drop sign (also called salmon patch or oil spot sign) is a pathognomonic nail change of psoriasis characterized by a yellow-brown translucent discoloration beneath the nail plate with a distinct border, resembling a drop of oil viewed through the nail. It corresponds histologically to foci of parakeratosis and serum exudate in the nail bed. Other nail changes in psoriasis include pitting, onycholysis, subungual hyperkeratosis, and red spots in the lunula. Nail involvement in psoriasis correlates strongly with psoriatic arthritis.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.