Myometrial Hyperplasia Mimics the Clinical Presentation of Uterine Fibroids

Abstract

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.