Management of Proximal Femur Aneurysmal Bone Cyst with 10-year Follow-up - A Case Report.

Introduction: Aneurysmal bone cyst is a benign, most often non-neoplastic lesion affecting the bone. Malignant transformation is reported in certain cases, although rare. It commonly occurs in young adults with around 75% of the cases occurring in the first two decades and 95% occurring in the first 3 decades. The management depends on the individual case parameters with ABC occurring in a weight-bearing area of a bone warranting an aggressive treatment plan with the consideration of preventing a pathological fracture.

Case Report: A 20-year-old male patient with no other comorbidities presented to us with complaints of atraumatic right hip pain of 9-month duration. On preliminary clinical examination and imaging studies with X-rays, CT scan, and MRI, the patient was diagnosed to have an aneurysmal bone cyst (ABC) of the right proximal femur. The patient was operated with intra-lesional excision with extended curettage and prophylactic fixation with DHS plating and kept on yearly follow-up. 10-year follow-up showed complete resolution of the lesion and implant removal was done after that.

Conclusion: As is clear from this case, the treatment of an aneurysmal bone cyst needs to individualized based on the patient's age, complaints, and tumor behavior in terms of its aggressiveness, size, and its extent. Often, en bloc excision with extensive curettage is required along with bone grafting and prophylactic fixation to support the bone graft and to prevent a pathological fracture and further recurrence. Implant removal if indicated should be done after complete resolution of the lesion, patient willingness, and any other medical indication.