Formation of a large rice body-containing cyst following total hip arthroplasty

BACKGROUND: There are several well-described causes of a painful mass following total hip arthroplasty including polyethylene and metal wear debris, infection, expanding hematoma, dislocation, and synovial cysts. In addition to causing pain, these lesions, when large enough, may cause neurologic and vascular compromise. Rapid growth of the mass may clinically and radiographically resemble a sarcoma. Here, we report a case of a large painful hip mass which developed after total hip arthroplasty. The well-circumscribed mass was overlying and extending into the hip joint containing thousands of highly organized fibrin-containing “rice bodies”. To our knowledge, this is the first report of a large, highly organized (rice-body-containing) cyst complicating total hip arthroplasty. CASE PRESENTATION: A 55-year old Caucasian woman developed a large, slowly enlarging, painful hip mass 2 1/2 years after primary total hip arthroplasty. Clinically and radiographically, the lesion resembled a soft tissue sarcoma. Surgical removal identified a well-circumscribed mass extending into the hip joint containing thousands of highly organized fibrin-containing “rice bodies”. CONCLUSION: Identification and excision of this “pseudotumor” following hip arthroplasty is important for obtaining a definitive diagnosis, ruling out malignancy or infection and relieving any potential compression on surrounding neurovascular structures.