CASE REPORTS: intraarticular fibroma of the tendon sheath in the knee.Clin Orthop Relat Res. 2005 Oct;439:280-5.

We report a rare case of fibroma of the tendon sheath in the knee. To our knowledge, only three previous cases of fibroma of the tendon sheath in the knee have been reported in the English literature. In our case, T1-weighted magnetic resonance imaging revealed a low intensity signal, T2-weighted magnetic resonance imaging showed a mixed area of high and low signal intensity, and gadolinium-diethylene triaminepentaacetic acid-enhanced magnetic resonance imaging showed faint enhancement at the periphery of the lesion. Magnetic resonance imaging therefore was valid for detection of this intraarticular lesion. The lesion, which was located between the posterior capsule of the left knee and the posterior cruciate ligament, was excised arthroscopically.

Intra-articular fibroma of tendon sheath of the shoulder joint: synovial fibroma.Skeletal Radiol. 2006 Aug;35(8):603-7. Epub 2005 Aug 20.

The case of a 30-year-old woman with multiple loose bodies in the shoulder joint is presented. The patient complained of discomfort of her right shoulder. Conventional radiographs failed to reveal any abnormality of the shoulder. On MRI numerous loose bodies were detected that resembled synovial chondromatosis. Histologically, the loose bodies were composed of a benign fibroblastic lesion with diagnostic features of fibroma of tendon sheath, each surfaced by synoviocytes. The clinicopathologic features of intra-articular fibroma of tendon sheath are reviewed. We propose using the term "synovial fibroma" for tumors with histopathologic features of fibroma of tendon sheath arising in the synovium of joints.