The case of a male 76 year-old patient with a history of total hip replacement surgery is presented herein. The patient had tumors in the iliac fossa with swelling of the thigh and pain upon hip flexion and extension. The complementary ultrasound and computed tomography show a large lobed cystic tumor in the left iliac fossa, 7 cm in diameter, close to the prosthesis. The diagnosis was psoas bursitis secondary to the release of polyethylene particles that caused compression and thrombosis of the superficial femoral vein. Cyst formation caused by polyethylene disease after total hip arthroplasty is infrequent.