Uterine-like mass with features of an extrauterine adenomyoma presenting 22 years after total abdominal hysterectomy-bilateral salpingo-oophorectomy: a case report and review of the literature.

Adenomyoma is a benign tumor composed of smooth muscle and benign endometrium. These tumors typically originate within the uterus. An extrauterine adenomyoma is a rare entity. We report a uterine-like mass consistent with an extrauterine adenomyoma presenting 22 years following a total abdominal hysterectomy and bilateral salpingo-oophorectomy. The mass was pear-shaped with uterine-type smooth muscle and a cavity lined by functional endometrial glands and stroma. To our knowledge, only 4 other cases of an extrauterine uterine-like mass are reported in the literature. Three involved the ovary, while one was located adjacent to the broad ligament with normal pelvic organs. Although none of these other uterus-like masses were described as adenomyomas with uterine-like features, the histologic findings are strikingly similar. An understanding of the müllerian system suggests that either an embryologic malformation or a differential multipotentiality existing in the subcoelomic tissues in response to hormonal stimulation results in a supernumerary müllerian structure like a uterus, as observed in this case. The presence of endometrial glands and stroma in the mass confirms that the tissues in this mass are hormonally responsive. It is most likely that this uterine-like mass arose from the tissues of the secondary müllerian system in response to estrogenic stimulation.