Juxta-articular myxoma: a clinical and pathologic study of 65 cases.

We describe 65 cases of juxta-articular myxoma (JAM) that occurred in the vicinity of large joints, possessed histologic features of a myxoma, and were frequently associated with cystic changes that resembled a ganglion cyst. The vast majority of cases (57, 88%) occurred in the region of the knee; a minority involved the shoulder (three cases), elbow (three), ankle (one), and hip (one) regions. Patients' ages ranged from 16 to 83 years (median, 43 years; mean, 44 years) and nearly three fourths of the patients (72%) were male. Thirty-seven lesions presented as a swelling or mass, 21 were associated with pain or tenderness, and sizes ranged from 0.6 to 12 cm (median, 3.5 cm; mean, 3.8 cm). Duration of symptoms was highly variable, spanning from 1 week to 18 years. Fourteen JAMs were intimately associated with the meniscus and five of these had a concomitant tear; in five other cases JAM was an incidental finding at the time of total knee or hip arthroplasty for severe osteoarthritis. Of 29 cases with follow-up, 10 (34%) recurred: five recurred once, two recurred twice, two recurred three times, and one recurred four times. While the majority of JAMs were correctly diagnosed as benign, a sarcoma was seriously considered or diagnosed in 15 (23%) cases.