Giant synovial cyst of the hip: an unusual presentation with compression of the femoral vessels.

A case of synovial cyst of the hip with symptomatic compression of the femoral vessels is described. A 75-year-old woman with severe unilateral osteoarthritis of the right hip was referred because of an intermittent, unpleasant sensation of coolness in the right foot and hip pain. A large mass was palpable in the femoral triangle. Computed tomography and arthrography revealed a large cyst communicating with the hip joint and compressing the femoral vessels ventrally. Total hip arthroplasty was carried out, and the stalk communicating with the cyst was ligated and divided. The unpleasant sensation of coolness in the right foot disappeared postoperatively. The authors concluded that iliopsoas bursitis should be considered in the evaluation of a patient with nonspecific pelvic or groin pain. As demonstrated in this rare case, the main symptom may be misleading and the typical syndrome of a tender groin mass with an underlying history of rheumatoid arthritis may be absent. Treatment should be directed to the underlying joint disease.