A 35-year-old man with psoriatic arthritis shows marked shortening of the left little finger with gross instability and redundant folds of overlying skin, giving a telescoping 'opera glass' appearance. Radiographs reveal extensive osteolysis of the phalanges with pencil-like tapering of the proximal phalanx. Which pattern of arthritis does this represent?
- A Symmetric polyarthritis mimicking rheumatoid disease
- B Asymmetric oligoarticular arthritis
- C Arthritis mutilans ✓
- D Axial spondyloarthropathy with peripheral dactylitis
Correct answer: C. Arthritis mutilans
Explanation
Arthritis mutilans is the destructive variant of psoriatic arthritis, occurring in roughly 5% of patients, characterized by aggressive osteolysis and resorption of the phalanges. Telescoping of the digit with redundant skin produces the opera glass (main en lorgnette) deformity. Asymmetric oligoarthritis is the commonest psoriatic pattern but preserves bone stock, and symmetric small-joint disease resembles rheumatoid arthritis yet lacks the gross acro-osteolysis that defines the mutilans pattern.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.