Pigmented villonodular synovitis of the talonavicular joint: a case report and review of the literature.

Pigmented villonodular synovitis (PVNS) is a locally aggressive synovial proliferative disorder of unknown aetiology affecting the linings of joints, tendon sheaths, and bursae. A 22-year-old female patient presented with a 3-year history of an increasingly painful swelling on the dorsum of her right foot. Examination revealed a 4 cm x 2 cm swelling that was fluctuant, tender on palpation, unattached to overlying skin and partially mobile. A firm, pedunculated intra-articular lesion from the talonavicular joint was removed at surgery. Histology revealed a nodular lesion of stromal cells and numerous giant cells with villous architecture as well as abundant haemosiderin deposition with foamy macrophages (in keeping with PVNS). The patient is currently under review by the orthopaedic oncology team. Talonavicular joint PVNS is rare. MRI scanning is the optimum investigation. Complete excision is necessary to minimise high risk of recurrence.