OSTEOBLASTOMA OF THE FOOT AND ANKLE

A total of 329 patients with osteoblastoma were retrospectively review ed from the archives of the Armed Forces Institute of Pathology, of wh ich 41 (12.5%) presented with tumors in the foot and ankle. This was t he third most common site of disease after the spine and femur. Overal l, the mean age was 22.5 years, which was the same for the foot and an kle subset of patients; however, there was a significant male predomin ance in foot and ankle patients compared with the whole group. The maj ority of patients were skeletally mature (85.4%). Clinically, most pat ients presented with pain (97.2%), although one-third of the total rel ated a history of antecedent trauma. The interval between the onset of symptoms and biopsy was 84 days (range, 0-572 days). Radiographically , the majority of lesions were in the hindfoot (N = 18; 44%) of which 16 of 18 tumors (89%) were in the talus. Of these, one-half were subpe riosteal and dorsally based and were associated with osseous tumor mat rix and a soft tissue mass. Two osteoblastomas, both in the metatarsal s, transitioned into sarcomas; the rest were histologically benign. Fo r diagnostic purposes, it was essential to obtain clinical, radiograph ic, and histologic correlation.