Case: A thirty-one-year-old woman presented with symptoms of worsening left knee and thigh pain. Radiographs and magnetic resonance imaging demonstrated extensive lytic and cystic changes throughout the femur. A biopsy demonstrated necrosis, chronic granulomatous inflammation, and laminations suggestive of an echinococcal cyst. Serology confirmed an Echinococcus granulosus infection. Treatment with anthelmintic agents was initiated, but reconstruction with a total femoral endoprosthesis was implemented as definitive management. The patient tolerated surgery well and returned for a one-year postoperative visit without evidence of recurrence of infection.
Conclusion: Osseous hydatidosis is a rare disease, but it should be included in the differential diagnosis of patients with extensive destructive bone processes.