Uterus-like mass of the small bowel mesentery

A case of a uterus-like mass arising from the mesentery is reported. A mass measuring 14x11 cm was noted in the small bowel mesentery of a 59-year-old woman. Histologically, the lesion consisted of endometrial-type and fallopian tube-type mucosa surrounded by thick bundles of smooth muscle cells. Since the first report by Cozzutto in 1981, 10 cases of uterus-like mass, that included seven ovarian and three extraovarian cases, have been reported. To our knowledge, the present lesion was the first case originating from the mesenteric region. Three hypotheses of this rare lesion: (i) congenital anomaly; (ii) metaplasia; and (iii) heterotopia theories are reviewed.