Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

Aneurysmal Bone Cyst: Clinical Features and Management

Overview

• Aneurysmal bone cyst is a benign, expansile, lytic bone lesion characterized by blood filled cavities separated by fibrous septa.
• It most commonly affects children and adolescents.

Common Locations

• Typical sites include the posterior elements of the vertebrae.
• Common long bone sites include the distal femur and proximal tibia.
• The lesion is usually located in the metaphysis.

Radiological Features

• Radiographs show an expansile lytic lesion with cortical thinning.
• The lesion may enlarge beyond the normal width of the bone.
• A thin periosteal rim is often present.
• Magnetic resonance imaging and computed tomography commonly demonstrate fluid fluid levels.

Pathogenesis

• The lesion may occur as a primary tumor with USP6 gene rearrangement.
• It may also arise secondarily in association with other lesions in approximately thirty percent of cases.
• Associated lesions include giant cell tumor, fibrous dysplasia, chondroblastoma, and chondromyxoid fibroma.

Histopathology

• The lesion consists of blood filled cystic spaces and fibrous septa.
• The septa may contain multinucleated giant cells and fibroblasts.

Differential Diagnosis

• Simple bone cyst.
• Telangiectatic osteosarcoma.
• Giant cell tumor.

Clinical Presentation

• Patients commonly present with pain and swelling.
• Pathological fracture may occur but is uncommon.
• Spinal lesions may produce neurological symptoms due to compression.

Management

• Initial care may include immobilization if fracture is present.
• Definitive treatment usually involves curettage with bone grafting.
• Adjuvant therapies may be used to reduce recurrence.

Recurrence

• Recurrence occurs in approximately twenty five percent of cases.
• The risk of recurrence is higher in patients with open growth plates.

Summary

• Aneurysmal bone cyst is a benign but locally aggressive lesion requiring appropriate diagnosis and treatment.
• Timely management reduces complications and recurrence.