Ossifying fibromyxoid tumor of soft parts: a case report.

A case of ossifying fibromyxoid tumor of soft tissue parts in the presacral region, which developed in a 46-year-old Japanese man is reported. The enucleated tumor was an encapsulated, elastic, hard mass measuring 2.5 x 2.2 x 1.4 cm. Microscopically, the tumor was characterized by foci of round to polygonal cells dispersed in a fibromyxoid matrix, containing varying amounts of collagen and osteoid tissue. At the marginal zone, the shell of bone and osteoid tissue with calcification separated the tumor from the surrounding tissues. Our patient is showing no evidence of recurrence after a one-year follow-up period. The findings are compatible with those proposed for ossifying fibromyxoid tumor of soft parts by Enzinger et al. in 1989. This tumor should be differentiated from cartilaginous, osteogenic and neural tumors.