A rare case of enchondromatosis of the knees and hands with involvement of Hoffa's fat pad and peri-articular soft-tissues.

We report a case of a 56-year old man with chronic pain in both knees for several years. This patient had already undergone surgery on his left knee in 2002 after an x-ray showed multiple lytic and well margined lesions in the distal femur and proximal tibia with ground-glass matrix, involving Hoffa's fat pad and the patellar ligament. Histology was consistent with an enchondroma. The most recent MRI examination showed enchondromatosis involving both knees with bilateral extension into Hoffa's fat pad and the patellar ligament. Subsequently, we performed an additional radiographic examination of the hands and feet, as well as an MRI of both hands to identify other possible enchondromas in the most common sites for this disease. Enchondromatosis with soft tissue involvement is extremely rare, and involvement of Hoffa's fat pad has not been reported in the scientific literature. The clinical presentation of this case and the general aspects of Enchondromatosis are discussed.