[Extensive hip joint ganglion as a rare cause of chronic pain in the groin].

A 66-year-old woman had complained for 6 months of worsening pain in the left groin with resultant difficulty in walking though there had not been any previous injury. MRI showed a cystic tumor extending from the left hip joint to the inner surface of the os ileum. CT-controlled puncture yielded a small volume of a gelatinous substance that was the content of the cyst, and bacteriological examination of this was negative. We resected the tumor using an ileofemoral approach. Histological examination showed that the tumor was a ganglion of the hip. These ganglia can grow very large without compressing vessels or nerves. They should be included in the diagnosis when patients present with chronic pain in the groin.