Review Question - QID 5543

This patient has onycholysis and pitting of the nail plate, characteristic of psoriasis. A characteristic hand deformity seen in psoriatic arthritis of the hands is seen in Figure D.

The characteristic psoriatic deformity is arthritis mutilans with opera glass deformity (la main en lorgnette) or telescoping joint destruction, so named because excess skin from the shortening of the phalanx bones becomes folded transversely, as if retracted into one another like opera glasses (retractable telescoping binoculars). Other findings in psoriatic arthritis of the hands include fluffy periostitis (caused by periosteal ossification), pencil-in-cup deformity (simultaneous destruction of the head of the middle phalanx and expansion of the base of the distal phalanx), acro-osteolysis (resorption of the distal phalanx tuft) and flail digits.

Day et al. reviewed psoriatic arthritis. This disease affects 6-48% of patients with psoriasis. Arthritis mutilans is found in 5% of patients and is destructive in 50%. Following surgery, wound infection rates are higher (skin plaques harbor bacteria) and wound healing may be complicated by the Koebner phenomenon (psoriatic outbreak following trauma) although healing rates are the same as normal skin. Periarticular bone loss may make reconstructive procedures challenging.

Figure A shows nail pitting and onycholysis (incomplete lifting of the nail plate starting at the distal free edge). Illustration A is a table showing the Psoriatic arthritis study group criteria for diagnosing psoriatic arthritis (3 or more points is indicative of psoriatic arthritis).

Incorrect Answers:
Answer 1: Figure B shows rheumatoid hands. There is a predilection for involvement of the PIPJ and MCPJ (especially 2nd and 3rd MCPJ), ulnar styloid and triquetrum, and sparing of the DIPJ. Characteristic findings seen include subchondral cyst, ulnar drift of the MCPJ, boutonniere and swan neck deformities, hitchhiker’s thumb deformity, carpal instability with scapholunate dissociation, and ulnar-carpal ankylosis.
Answer 2: Figure C shows erosive osteoarthritis. The DIPJ, PIPJ and 1st CMCJ are involved. Characteristic findings seen include diffuse cartilage space loss, subchondral erosions (at least 2 central erosions affecting separate IP joints), central erosions producing "gull wing" appearance, absence of marginal erosions, fusiform soft-tissue swelling and osteopenia.
Answer 4: Figure E shows the hands of a patient with gout. Characteristic findings include periarticular osteopaenia, eccentric erosions (well-defined marginal/juxta-articular punched-out rat-bite erosions with sclerotic margins with overhanging edges, and periarticular soft tissue swelling and tophi deposition. Tophi can calcify in the presence of renal disease.
Answer 5: Figure F is a radiograph of a patient with Dupuytren's disease with contractures of the small finger MCPJ and PIPJ.