Malignant mixed mesodermal tumour of the peritoneum with a complete response to cyclophosphamide.

We treated a 66-year-old Japanese woman with malignant mixed mesodermal tumour of the heterologous type arising from the paracolic peritoneum. The tumour contained heterologous elements in the form of cartilage in addition to carcinosarcomatous areas. This is the third case of malignant mixed mesodermal tumours originating from the peritoneum to be documented in the literature. A complete resection of the tumour was carried out but multiple lymph nodes metastases in the left neck occurred 5 months later. Cyclophosphamide in doses of 150 mg daily by mouth was initiated, with the result of a complete regression of the malignant lesions. She died of myocardial infarction 21 months after surgery.