A patient with psoriasis has nail changes showing oil-drop/salmon patch, onycholysis, and subungual hyperkeratosis. The nail finding most specific to psoriatic nail disease (and correlating most strongly with psoriatic arthritis) is:

• A Beau's lines
• B Onychomadesis
• C Geometric pitting (large, irregular pits in regular rows) ✓
• D Yellow nail syndrome (slow-growing, curved yellow nails)

Explanation

Psoriatic nail disease (present in 50% of psoriasis patients, up to 90% of those with psoriatic arthritis) causes multiple findings. Geometric or 'large, irregular' pitting — in contrast to the small, uniform thimble pits of alopecia areata — is most specific to psoriasis. Onycholysis and oil-drop sign (due to psoriatic changes in the hyponychium/nail bed) are also characteristic. Nail psoriasis is the strongest clinical predictor of psoriatic arthritis. Beau's lines are transverse grooves from any systemic illness.

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.