A patient with psoriasis develops asymmetric inflammatory arthritis affecting DIP joints and sacroiliac joints. HLA association and the nail finding most predictive of psoriatic arthritis are respectively:
- A HLA-B27; nail pitting (>20 pits) ✓
- B HLA-B27; pitting
- C HLA-Cw6; onycholysis
- D HLA-DR3; leukonychia
Explanation
Psoriatic arthritis (PsA) is associated with HLA-B27 especially the axial (spondylitic) pattern affecting sacroiliac joints. The nail finding most predictive of PsA is pitting — more than 20 nail pits is highly associated with PsA risk. Nail involvement (pitting, onycholysis, subungual hyperkeratosis) is found in up to 80% of PsA patients compared with 40% in psoriasis without arthritis. HLA-Cw6 is the major psoriasis susceptibility gene for skin disease but is not the dominant association for the arthritis. Onycholysis is less specific for PsA prediction compared to multiple nail pits.
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.