Pelvic pseudotumor: an unusual presentation of an extra-articular granuloma in a well-fixed total hip arthroplasty.

A 76-year-old woman developed a pelvic mass and abdominal pain 12 years after cementless total hip arthroplasty. The mass was a cystic granuloma that communicated with the hip joint via a soft tissue herniation under the inguinal ligament. There was no acetabular lysis or defects. The shell and femoral component were well fixed, the polyethylene was worn, and a liner exchange was undertaken. The cyst was debrided, and follow-up computed tomography demonstrated resolution of the granuloma and no recurrence of the cyst. Removal of the source of the particle wear debris via liner exchange or revision surgery combined with cyst debridement via a single incision is recommended.