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Chondroblastoma of trapezium with metacarpal involvement.

Chondroblastomas typically affect the epiphysis of the long bones in young patients, and only rarely occur in the elderly >70 years. Approximately 10% to 20% of chondroblastomas are located in the small bones of the hands or feet, however, they are rare in the carpal bones. Chondroblastoma is a benign tumor, but it may show not only aggressive clinical course but also pulmonary metastases. We report a case of chondroblastoma in a 75-year-old woman that originated in the right trapezium, involving the proximal half of the first metacarpal. She had noticed a mass in her right wrist for approximately 1 year before presenting to the hospital. Radiologically, a large lytic tumor was observed in the right trapezium, with marked expansion of the cortex. On magnetic resonance imaging and computed tomography, the tumor extended from the trapezium into the proximal half of the first metacarpal. Resection of the trapezium and a half of the first metacarpal was performed. Histologically, typical chondroblastoma with small foci of secondary aneurysmal bone cyst was noted. This is an unusual case of chondroblastoma, originating in the carpal bones of an elderly individual, and involving adjacent bone. Benign chondroblastomas of unusual sites may show locally aggressive features, and benign chondroblastomas may occur in elderly persons.