True about synovial chondromatosis is?

Ans CPrimary synovial chondromatosis is a type of non-cancerous monoarticular lesion of unknown etiology that arises from synovial metaplasia of a joint. The knee is most commonly affected, however it can affect any joint. The tumors begin as small nodules of cartilage of similar sizes. These nodules can separate and become loose within the joint. Synovial chondromatosis most commonly occurs in adults ages 20 to 50. Treatment may involve surgery to remove the lesions. Recurrence is common.