Psoriatic arthritis classically involves:

Ans: b (DIPjoint) Ref: Maheswari, 3rd ed, p. 251Psoriatic arthropathy is polyarthritis & distal IP joints are typically involved.(Unlike rheumatoid arthritis, where these are spared)Psoriatic arthritis can present with a wide spectrum of clinical features namely1) Asymmetrical inflammatory oligoarthritis - 40%2) Symmetrical polyarthritis - 25%3) Predominant distal interphalangeal joint arthritis -15%4) Psoriatic spondy 1 itis -15%5) Arthritis mutilans - 5%. It is the most serious condition and the skin of fingers appears telescoped.NoteOsteoarthritis - involves PIP, DIP and 1st carpometacarpal joint (base of thumb). Spares MCP and wrist.Rheumatoid arthritis-involves any small joint of hand e.g., PIP. MCP, wrist. Sparing of DIP.Psoriatic arthritis - involvement of PIP. DIP, MCP and wrist. Sparing of any joint may or may not be present.If DIP is involved rheumatoid arthritis can be ruled out.Similarly if MCP joint is involved osteoarthritis can be ruled out.