Adenosarcoma of the uterus: ultrastructural observations.

Müllerian adenosarcoma has been recently described as a distinctive biphasic uterine tumor with benign epithelial and malignant stromal components. The lesion belongs generally to the group of mixed müllerian tumors, but the benignity of the epithelium separates it from the other neoplasms of this type. This entity usually affects postmenopausal patients who follow a protracted course. This paper reports a case fulfilling the original clinical and pathologic description of Clement and Scully and adds ultrastructural observations. Electron microscopic examination confirmed the optical impression of a biphasic neoplasm with benign epithelial and malignant stromal components. The epithelium resembled proliferative endometrium, and the stroma had features of endometrial stromal sarcoma or mixed müllerian tumor. The findings of stromal resemblance to endometrial stromal sarcoma or mixed müllerian tumor and the presence of a variety of müllerian epithelia support the proposed müllerian derivation of this lesion.