Malignant mixed mesodermal tumour of the uterus initially confined to a polyp

A malignant mixed mesodermal tumour (MMMT) of the uterus, in a 68-year-old woman, was initially confined to an endometrial polyp. Despite the absence of myometrial invasion, the tumour metastasized to the omentum. This experience conflicts with previously reported cases. An aggressive approach to the management of these tumours is suggested.