A 62-year-old male patient, farmer by occupation, presented to the orthopedic outpatient department with the complaint of painful gluteal mass with restricted hip movement for the past 12 years. He had undergone incision and drainage on couple of occasions at a local health-care center. On both of those occasions after a brief period of symptomatic relief, painful swelling reoccurred. On physical examination, a large cystic swelling associated with pain and reduced hip movement was observed over the left gluteal region. With the suspicion of osteoarticular tuberculosis, he had undergone antitubercular therapy without any symptomatic relief from the local hospital. Thus, osteoarticular tuberculosis was kept much lower as a differential diagnosis in this case.
Plain radiograph revealed reduced joint space and cystic lesion with destruction of ischial tuberosity, acetabulum, and femoral head [Figure 1]. Other routine investigations revealed elevated erythrocyte sedimentation rate, C-reactive protein, and eosinophilia with absolute eosinophil count of 730/ml. Renal and liver function tests were found to be under normal range.
Serum sample was received by the department of microbiology for hydatid serology to rule out possible parasitic infection. Hydatid serology using immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) (RIDASCREEN Echinococcus IgG, R-Biopharm AG, Germany) was performed following the manufacturer's instruction, and surprisingly, the optical density value was above the cutoff. Hydatid serology result was further correlated with computer tomography scan (CT-scan) and magnetic resonance imaging (MRI) of the pelvis. CT-scan and MRI revealed a multiloculated cyst with destruction of left ischial tuberosity, acetabulum, and femoral head. Few calcified foci were also noted supporting positive hydatid serology.
Based on the above serological and radiological findings, a provisional diagnosis of primary pelvic hydatidosis was made. Surgery was planned and the patient underwent preoperative albendazole chemotherapy, followed by en bloc mass excision of the cyst without rupturing the cyst wall. The removed tissue with a cyst was sent to the department of pathology for histopathological analysis. Hematoxylin and eosin stainingrevealed a thick cyst wall with few daughter cysts, occasional calcified foci with intense inflammatory responses, and exuberant giant cell reaction against lamellated membranes [Figures 2 and 3] consistent with hydatid cyst. Postoperative period was uneventful and was subsequently discharged with advice of albendazole (10 mg/kg) chemotherapy for 3 months with a regular follow-up. During his last follow-up, the patient had no fresh complaints. He had better hip movement without pain and was walking with support.