Intraarticular fibroma of the tendon sheath arising from the infrapatellar fat pad in the knee joint.

We report a rare case of fibroma of the tendon sheath arising from the fat pad in the knee. To our knowledge, only four previous cases of fibroma of the tendon sheath in the knee have been reported in the English literature. In our case, magnetic resonance imaging showed low signal intensity in the mass on T1- and T2-weighted images. The mass was excised by mini arthrotomy.