Fibroma of the Patellar Tendon Sheath: A New Paradigm.

The authors present a case of fibroma of the tendon sheath with intra-articular location in the knee, more specifically in the infrapatellar fat; with this specific location, this is the fourth case described of an entity that rarely affects large joints. Clinical and epidemiological aspects, but especially the imaging findings on magnetic resonance imaging scans, are essential for the differential and definitive diagnosis, which was nevertheless established only after a histological study of the excised mass by miniarthrotomy.