Fine needle aspiration cytology of chondroblastoma of bone

Between 1979 and 1987 12 patients with chondroblastoma underwent fine needle aspiration (FNA). There were eight female and four male patients (age range, 11-35 years) with lesions of the proximal humerus (three cases), distal femur (two cases), proximal tibia (two cases), proximal femur, distal tibia, talus, navicular bone, and fifth metacarpal (one case each). The radiologic features of the tumors were not entirely typical of chondroblastoma in the majority of patients. The aspirate was diagnosed as chondroblastoma in seven cases, was considered strongly suggestive of chondroblastoma in one case, was found to be diagnosable as chondroblastoma on review in one case, and was nondiagnostic in two cases. The remaining case, which showed giant cell tumor-like areas in addition to typical chondroblastoma on histologic sections from the curettage, was interpreted as giant cell tumor on FNA. There was no case in which an aspirate was erroneously diagnosed as chondroblastoma. On FNA, chondroblastoma had three dominant cytologic components: neoplastic mononuclear cells (chondroblasts), multinucleated osteoclast-like giant cells, and chondroid matrix fragments. The chondroblasts tended to lie individually in smears creating a pebbled appearance. They most commonly had round to oval nuclei with fine, evenly distributed chromatin and distinct longitudinal grooves, but indented, lobulated, and pyknotic nuclei were also observed. Their cytoplasm was dense and opaque with rounded well-defined borders. Multinucleated osteoclast-like giant cells were randomly admixed and were indistinguishable from those seen in other bone neoplasms. Chondroid matrix stained magenta with the Diff-Quik stain and green to violet with Papanicolaou. The cytologic features of the chondroblasts are the diagnostic hallmark of chondroblastoma and may allow FNA to become a valuable preoperative technique in the management of these patients.