Which of the following is NOT typical for psoriatic arthritis?

• A. Dactylitis
• B. Arthritis mutilans
• C. DIP involvement
• D. Vespertilio

Answer: (D)

Psoriatic arthritis (PsA) covers a range of inflammatory joint manifestations that accompany psoriasis. Dactylitis, the sausage-like swelling of an entire finger or toe from combined joint and soft-tissue inflammation, is a classic feature. Arthritis mutilans is a recognized though uncommon, highly destructive form of PsA that can cause telescoping of the digits. Involvement of the distal interphalangeal joints is also common in PsA and helps distinguish it from rheumatoid arthritis, where DIP involvement is less typical. The term vespertilio has no basis as a clinical manifestation of psoriatic arthritis, so it does not fit with the patterns seen in PsA. Therefore, vespertilio is not a typical feature.