Recurrent Aneurysmal Bone Cyst of Proximal Femur with Pathological Fracture - A Case Report.

Introduction: Aneurysmal bone cyst (ABC) is a rare, benign, and cystic lesion. The most common sites are the femur, tibia, humerus, and spine. It is more common in females and usually occurs during the second decade of life. Case Report: A 5-year-old female child had a trivial fall, following which she developed pain in her left hip. Radiographs revealed an expansile, lytic lesion in the metaphysis of the left proximal femur. Cortical breach was present resulting in a pathological fracture. Biopsy of the lesion showed blood filled cystic spaces confirming the diagnosis of ABC. We performed an extended curettage of the lesion, bone grafting, and angle blade plate fixation. The angle blade plate was removed 1 year after the surgery. Two years later, she complained of pain in the left hip. Radiographs showed a geographic lytic lesion surrounding the previously inserted bone graft. Magnetic resonance imaging revealed multiple blood fluid levels. We performed an extended curettage with high speed burr. We filled the cavity with bone substitute and stabilized the region using a proximal humerus internal locking system plate. The histopathological examination of intraoperative samples confirmed the diagnosis of recurrence of ABC. We found no further recurrence of the tumor after 3 years of follow-up. Conclusion: ABCs can present with pathological fractures and requires management of the cyst and stabilization of the bone. Recurrent ABCs can be managed by re-curettage of the lesion and prophylactic internal fixation. The curettage has to be extensive through a large cortical window and using a high speed burr.