To evaluate the clinical manifestations and results of treatment, we have analyzed five cases of Pigmented villonodular synovitis (PVNS) involving the ankle joint, a very rare disease in which the intraarticular joint has active inflammation with hypertrophy of the synovium.

From January 2002 to July 2004, five patients who presented with a mass in the ankle joint had histopathologically confirmed PVNS, retrospectively identified after surgery. Four male patients and one female patient were included in the study. All five patients had preoperative ankle joint swelling and a mass without a history of trauma; all had standard x-rays and three of the five patients had Magnetic resonance imaging (MRI).

As a result of the testing there were two localized and three diffuse types identified. For one diffuse type, arthroscopy assisted intraarticular synovectomy was carried out before invasive synovectomy. Mass excision and broad synovectomy were carried out in all cases, and histological evaluations were performed after surgery. For two cases that had incomplete synovectomy, due to adhesions surrounding soft tissue and severe bony invasion, the surgical region was simultaneously treated with postoperative radiation therapy. After an average postoperative follow-up period of 13 months, the pain, swelling and edema resolved and there were no signs of recurrence.

Mass excision and broad synovectomy provided both accurate diagnosis and successful treatment of PVNS of the ankle joint. In cases where incomplete synovectomy is performed due to anatomical difficulties or bony invasion, combination with postoperative radiation therapy may help reduce the recurrence rate.