Metadiaphyseal chondroblastoma of the thumb

Chondroblastoma is typically located in the epiphysis. Predominant metadiaphyseal location is very rare, as is involvement of the digits. We describe a case of chondroblastoma involving the metadiaphysis of the thumb. The patient was a 13-year-old boy who presented with pain and swelling of his left thumb. Radiographs showed an expanded lytic lesion involving the whole metaphysis and diaphysis of the proximal phalanx, which subsequently progressed to involve the epiphysis. Curettage and bone grafting were done.