A case of aneurysmal bone cyst of the vertebrae

We report the case of aneurysmal bone cyst (ABC) of the vertebrae in a 11-year-old girl. Radiographic results suggested ABC or osteosarcoma. Intraoperative pathological examination showed slit-like spaces separated by cellular and collagenous fibrous tissue including some osteoclast-like giant cells and numerous fibroblastic cells, with bone and osteoid tissue present. Imprint cytology showed some atypia-free osteoclast-like giant and fibroblastic cells against a bloody background, diagnosed as aneurysmal bone cyst. Although we consider ABC, giant cell reparative granuloma, conventional giant cell bone tumor, and osteosarcoma included in the differential diagnosis, cytological findings were useful in diagnosis, especially distinguishing between benign cells and malignancy.