Tenosynovial fibroma arising from the posterior cruciate ligament.

In a 16-year-old girl, a locking and effusion of the left knee occurred without a history of any specific trauma. Arthroscopic examination of the knee revealed a soft tissue mass arising from the posterior cruciate ligament. The mass was completely excised, arthroscopically. The microscopic diagnosis was tenosynovial fibroma, a new entity reported by Chung and Enzinger in 1979. After a follow-up study of 20 months, the patient was asymptomatic.