Diffuse pigmented villonodular synovitis (PVNS) is a rare benign disorder characterized by an exuberant inflammation on synovial membrane. The purpose of this study was to report clinical manifestations and the results of treatment in eight cases of PVNS.

Eight patients presenting with PVNS were analyzed from the patient records and the pathologic records. The seven of the patients had been managed with arthroscopic synovectomy and one patient underwent open synovectomy and total joint replacement. Four of the eight patients had magnetic resonance imagings (MRI). Recurrence after synovectomy was considered to have occurred, if there were noteworthy clinical symptoms and signs.

The average age of the eight patients with PVNS was thirty years-old. They complained of nonspecific pain and discomfort. Four knees on MRI scans had irregularity with loss and deformity of the intracapsular fat pad (infrapatellar, the suprapatellar and the quadriceps fat pad). Recurrence occurred in three of the eight patients (one total synovectomy, two partial synovectomy).

We observed characteristic changes in the intracapsular fat pads on the MR images of patients with PVNS. The recurrence rate was high after arthroscopic synovectomy.