A 45-year-old man with chronic plaque psoriasis develops asymmetric arthritis affecting the distal interphalangeal joints and nails with onycholysis. Radiographs show severe erosions with pencil-in-cup deformity. Which feature most strongly distinguishes this from rheumatoid arthritis?
- A Distal interphalangeal joint involvement with nail changes ✓
- B Symmetric involvement of small joints
- C Presence of rheumatoid nodules
- D Morning stiffness lasting more than 1 hour
Correct answer: A. Distal interphalangeal joint involvement with nail changes
Explanation
Psoriatic arthritis preferentially involves DIP joints unlike RA which spares them, and is associated with nail changes like pitting and onycholysis. RA typically involves MCP and PIP joints symmetrically. Morning stiffness and rheumatoid nodules can occur in both conditions.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.