Outcome following radiation treatment for high-risk pigmented villonodular synovitis

Pigmented villonodular synovitis (PVNS) is a rare proliferative process involving synovial membranes. It has a variable course, and while usually benign, may be destructive, resulting in major symptoms and loss of function leading to amputation. Optimum treatment is not always clear, and little information exists with respect to the role of radiotherapy. The purpose was to review our experience with radiotherapy in cases at high risk for recurrence with functional loss including instances where amputation was the sole alternative for symptomatic disease.

The records of all patients registered between 1972 and 1992 with a diagnosis of PVNS were identified (21 cases). The records of 14 cases who received radiotherapy after referral were reviewed retrospectively for demographic information, radiotherapy treatment parameters, and tumor outcome.

All cases had confirmation of pathologic diagnosis. Six patients had primary and eight had recurrent disease (with a mean of 2.5 prior surgical procedures). All cases had both intra- and extraarticular disease and, without exception, the poorer prognosis diffuse subtype of the disease. The majority had one or more additional risk factors including skin, bone, tendon, neurovascular, or muscle group extension. With a mean follow-up time of 69 months (range 13-250 months), only one patient has shown persistence of disease. With the exception of that single case, all those with measurable disease had obvious disease until at least 12 months and, subsequently, manifested complete responses. The single case was lost from the clinic after 8 months from the initiation of radiotherapy to a dose of 30 Gy in 15 fractions and had a palpable mass at the time. He subsequently was noted to have a persisting mass and an excisional biopsy 9 years later showed PVNS. He remains well 21 years after treatment with good function. Eleven patients enjoyed excellent or good function from the affected limb and three had fair function. All patients had greater use of limb than at the time of treatment. No patient required amputation, and none had evidence of serious radiotherapy complications.

These results demonstrate that moderate dose radiotherapy is an effective modality in the treatment of a subset of cases with this rare condition. Its use has permitted avoidance of amputation in very advanced cases with acceptable function preservation. When treatment is indicated we currently recommend gross total removal of PVNS. This is followed by moderate dose radiotherapy (35 Gy in 15 fractions) for residual disease where salvage of subsequent recurrence may compromise function.