Myometrial hyperplasia mimics the clinical presentation of uterine fibroids: a report of 3 cases.

The clinical diagnosis of fibroid uterus is based on physical examination findings and/or ultrasound. However, it is not uncommon for routine pathology examination to report no significant fibroids in such cases. Myometrial hyperplasia (MMH) is a structural variation with irregular zones of hypercellularity and increased nucleus/cell ratio that appears in adolescence, can progress during the childbearing years, and can sometimes cause grossly detectable bulges on pathologic examination. MMH can be inframucosal, intramural (microscopic), or subserosal. Three premenopausal women with a preoperative diagnosis of fibroids on pelvic examination, and/or sonograms, underwent hysterectomies. In all the 3 cases, the Myoma Index (number of fibroids×size of largest fibroid) indicated insignificant fibroids. The pathology simulating fibroids was firm, bulging inframucosal MMH. Firm, bulging MMH can mimic uterine fibroids on ultrasound and physical examination. In hysterectomies for fibroid uterus with a Myoma Index <3.7, it is recommended that pathologists evaluate for MMH as the possible explanation for the findings on physical examination and/or ultrasound.

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.