Aggressive granulomatous lesion presenting as tumor in cementless long stem total hip arthroplasty

We describe a patient with an aggressive granulomatous lesion around a cementless total hip prosthesis, which simulated a tumor. The granuloma showed a uniform histopathology, which included mononuclear cells and metal wear particles. Aggressive granulomatous lesions in replaced hips are a distinct condition, different from simple loosening or infection; the lesions may grow rapidly, so that revision surgery is indicated soon after diagnosis.