A 59-year-old man with ischemic pancreatic disease, polyarthritis, and cutaneous nodules has shown histopathologic findings indicative of disseminated fat necrosis in a percutaneous biopsy specimen from the right knee. The histopathologic findings in the synovium included necrotic fat cells, distorted fat cells and adjacent lymphocytes, lipid laden histiocytes, and giant cells. In prior histopathologic studies of the joint involvement associated with this disorder, fat cell necrosis has been found only in the periarticular tissues, and the synovium has appeared normal or showed nonspecific inflammation. However, the present study shows that the synovial membrane may also be the site of fat necrosis and an associated inflammatory reaction; thus patients with this disorder may manifest arthritis in addition to periarthritis.