A patient with psoriasis shows nail changes: oil-drop discoloration (salmon patches) under the nail plate, onycholysis, and nail pitting. Nail pitting in psoriasis correlates histologically with:
- A Eosinophilic infiltration of the nail bed
- B Onychomycosis superimposed on psoriasis
- C Parakeratotic foci in the nail matrix causing surface depressions ✓
- D Type IV collagen deficiency in nail plate
Correct answer: C. Parakeratotic foci in the nail matrix causing surface depressions
Explanation
Nail pitting in psoriasis results from focal parakeratosis in the proximal nail matrix (proximal nail matrix defect produces pits in the nail surface). As the nail grows, these parakeratotic foci fall out, leaving surface pits. Oil-drop/salmon patches arise from psoriasis of the nail bed (distal matrix/nail bed involvement). Onycholysis results from subungual hyperkeratosis lifting the nail plate. These features are collectively seen in 80% of psoriatic arthritis patients.
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.