Fine-needle aspiration cytology of chondroblastoma of soft parts: case report and differential diagnosis with other soft tissue tumors.

Chondroblastoma is a benign tumor arising in the epiphysis of long bones. The extraskeletal presentation is most unusual. We report the first cytological description of a soft tissue chondroblastoma. It was a subcutaneous mass in the leg of a 62-yr-old man. Fine-needle aspiration (FNA) rendered a highly cellular material with grouped and single polygonal or round cells with a uniform, sometimes eccentric nucleus. Microvacuolated cytoplasm and hemosiderin pigment were frequent findings. There were rare nuclear grooves and mitoses. A metachromatic, focally calcified stroma was present, occasionally surrounding the cells. There were also numerous multinucleated osteoclast-like giant cells. Histological evaluation was diagnostic of chondroblastoma. The tumor was locally aggressive. A review of other soft tissue masses with similar cytological findings is included in the discussion. FNA cytology is very helpful in the diagnosis of soft tissue chondroblastoma, but additional studies may be necessary for a definitive diagnosis.