Localised pigmented villonodular synovitis: an uncommon cause of knee pain mimicking a meniscal tear.

A previously well 30 year old man presented with a short history of intra-articular mechanical locking, swelling, and anteromedial joint line pain. There was localised tenderness, and McMurray's test was positive. Arthroscopy revealed a 3.6 x 2.6 x 1.5 cm firm pedicular localised pigmented villonodular synovitis originating from the insertion of the anterior horn of the medial meniscus. Owing to its size and consistency, mini-arthrotomy was required. This allowed a return to sporting activities. Localised pigmented villonodular synovitis can mimic symptoms of a meniscal tear.