Failed metal-on-metal total hip arthroplasty presenting as painful groin mass with associated weight loss and night sweats.

We report an unusual case of a failed metal-on-metal total hip arthroplasty presenting as a groin mass with associated weight loss, night sweats, and raised inflammatory markers. After a malignant process was ruled out, the patient was found to have a loose acetabular component. Histopathologic results revealed features of an aseptic lymphocytic vasculitic associated lesion. All symptoms resolved completely after the metal-on-metal bearing was revised to metal-on-polyethylene.