Eleven patients with hemangioma of the synovial membrane have been seen at the Mayo Clinic from 1907 through 1956. The tumor occurred in the knee in nine patients, and in the ankle and elbow, respectively, in two others. These patients represent the first reported instances of involvement of these joints. The results of this study suggest that synovial hemangioma should be suspected if the patient is young, symptoms are of long duration, pain and swelling occur intermittently (usually without obvious cause), and the patient presents an exquisitely tender mass that feels soft and doughy, increases in size when in a dependent position, and decreases in size on elevation.
Prognosis following surgical excision of these tumors appears to depend on the feasibility of complete excision of the tumor and not on any inherent pathological characteristics of the tumor itself.