Subungual chondroblastoma in a 9-year-old girl.

Chondroblastoma is an uncommon primary bone tumor, mainly found in the epiphyses of long bones. We describe a 9-year-old girl who presented with a chondroblastoma as a subungual mass in the fifth toe. Radiographs showed an expansive, calcified tumor of the distal phalanx. Histologic examination after excision revealed chondroid differentiation, active mitosis, multinucleated giant cells, calcification, and necrosis. There was no recurrence of the lesion after surgical excision. The purpose of this report is to document this unusual event that occurred in such a short bone as the distal phalanx of the fifth toe, mimicking a dermatologic entity.