Adenosarcoma of uterus, light micrograph. Mullerian adenosarcoma of the uterus is a biphasic tumour consisting of sarcomatous stroma and a benign glandular component. The sarcomatous stroma is usually low-grade. It forms a polypoid mass that can fill up the endometrial cavity. At intermediate magnification as shown here, the broad, leaf-like polypoid architecture creates a striking resemblance to phyllodes tumour of the breast.