Uncommon Primary Synovial Chondromatosis Involving Only the Infrapatellar Fat Pad in an Elderly Patient.

Primary synovial chondromatosis is a rare condition of idiopathic synovial chondrometaplasia and usually occurs during the third to fifth decades of life. Conversely, secondary synovial chondromatosis results from the growth of separated particles from articular cartilage or osteophytes in patients with joint diseases, such as degenerative osteoarthritis, and occurs mostly in elderly people. We describe here a 76-year-old male histopathologically confirmed as having primary synovial chondromatosis with no calcification of the infrapatellar fat pad (IFP) of the knee joint. To our knowledge, this is the first description of primary synovial chondromatosis of the knee joint confined to the IFP in a patient >60 years old.