Malignant ectomesenchymoma of soft tissue. Report of two cases and review of the literature.

The clinical and pathologic findings of two patients with malignant ectomesenchymomas of soft tissue are reported. Malignant ectomesenchymomas are a composite of ganglion cells or neuroblasts and one or more malignant mesenchymal elements, usually rhabdomyosarcoma. Our first case was composed of ganglioneurosarcoma plus rhabdomyosarcoma, the second composed of neuroblastoma plus rhabdomyosarcoma. The name is derived from the suggestion that they arise from pluripotential ectomesenchyme. An English language literature search revealed 11 other cases that arose in soft tissue and had adequate clinicopathologic data. Of the 13 cases, 10 occurred in infants, three occurred in adults, and nine were males. Six patients were alive and free of disease at last follow-up (range, 0.6-12 years; mean, 3.4 years), four patients had died of tumor (within 0.5-3.3 years; mean, 1.3 years), one case had died of Adriamycin (doxorubicin) toxicity, and two cases had been lost to follow-up. Complete surgical resection is the mainstay of treatment and chemotherapy appears to be important.