Myometrial dysplasia (atypical myometrial hyperplasia).

Although precursor lesions are well known for cervical and endometrial neoplasms, precursor lesions are not currently recognized for the most common tumor of the uterus-leiomyomas. Myometrial hyperplasia has been recently described and evaluated by morphometry, but its relationship to uterine leiomyomas has not been systematically explored. Myometrial dysplasia (atypical myometrial hyperplasia) has not been previously recognized. We herein report a case of myometrial dysplasia with immunostains for proliferation marker MIB-1 (Ki-67) and for p53. The paradoxical rarity of myometrial dysplasia is considered in comparison to the striking frequency of uterine leiomyomas.