Parosteal extra-axial chordoma of the second metacarpal bone: a case report with literature review.

Extra-axial chordoma is a chordoma that occurs in non-axial locations. It is a very rare tumor, with 20 cases reported to date; 14 in bone and six in soft tissue. Of the 14 skeletal extra-axial chordomas, ten were intramedullary and four were intracortical. We report the first case of parosteal extra-axial chordoma arising in the second metacarpal bone, expressing brachyury on immunohistochemical analysis, and describe the pathologic and radiologic findings. We suggest that extra-axial chordoma can occur in parosteal bone lesions or the hand, without features of bone distribution or bone-specific sites.