Compression of bladder due to 'rheumatoid' cysts of hip joint

Large, bilateral, pelvic, cystic masses were present in a 43 year old man with chronic rheumatoid arthritis. The cysts arose from the hip joints and compressed the bladder with resultant urinary symptoms. Biopsy indicated that their histologic appearance was compatible with that of "rheumatoid cysts," and the symptoms were controlled with steroid therapy. The location, size, and compressive effects of these cysts make this a unique case.