[Adenomatoid tumors of the uterus. Study of 5 cases with immunohistochemical and ultrastructural confirmation of the mesothelial origin].

Five cases of adenomatoid tumors of the uterus (ATU) are reported. These benign lesions are discovered in 1% of the hysterectomy specimens, performed on 20- to 85-years-old women. Their frequency is certainly underestimated, since ATU have the same macroscopic appearance as leiomyomas. Histologically, ATU are formed by gland-like and pseudovascular lumens, lined by regular, cuboidal or flattened cells, and surrounded by hyperplastic smooth muscle bundles. Immunohistochemical coexpression of cytokeratin and vimentin confirms with a mesothelial histogenesis. The ultrastructural study, showing luminal microvilli and desmosomes supports the hamartomatous development of ATU, corresponding to mesothelial inclusions from the peritoneum into the myometrium. Some giant or diffuse ATU, which are clinically disturbing, are differentiated from carcinomatous or vascular proliferations by frozen section examination. The treatment is made by surgical excision.