Ossifying fibromyxoid tumor of soft parts in a child: a case report.

Ossifying fibromyxoid tumor (OFMT) is a relatively rare tumor, most of which occur in adults with preferential localization in subcutis or muscles of the extremeties. Although Schwannian or cartilage origin has been suggested, histogenesis of this tumor still is unclear. The authors present a 6-year-old girl with retroperitoneal OFMT showing paraspinal extension, who is alive and tumor free 9 years after excision. The current case is the youngest reported patient showing unusual deep trunk site with surgically identified association with the spinal nerve. Both the clinical and histopathologic features strongly suggested Schwannian origin of this tumor.