Imaging in gynecological disease (30): clinical and ultrasound characteristics of usual‐type and variants of leiomyoma

ABSTRACT Objective To characterize the clinical and ultrasound features of usual‐type leiomyoma and variants of leiomyoma. Methods This retrospective, single‐center study included patients with a histologically confirmed diagnosis of benign mesenchymal uterine tumor, prospectively collected between January 2019 and December 2021 in the MYometrial Lesion UltrasouNd And mRi (MYLUNAR) study. Tumors were classified according to the Morphological Uterus Sonographic Assessment criteria and grouped according to the 2020 World Health Organization (WHO) classification of female genital tumors into usual‐type and variant leiomyomas. The variants of leiomyoma were further classified into specific histological subtypes as defined in the WHO classification. Two ultrasound examiners independently reviewed all available ultrasound images to identify patterns associated with usual‐type leiomyoma and variants of leiomyoma. Results A total of 1766 patients were included, of whom 1383 (78.3%) had usual‐type leiomyoma and 383 (21.7%) had a variant of leiomyoma. The median age at diagnosis was 45 (range, 15–88) years, with no statistically significant difference between the two groups. Most patients were premenopausal, although the variant group had a higher proportion of postmenopausal patients compared with the usual‐type group (21.5% vs 12.6%; P < 0.001). On ultrasound examination, leiomyoma variants were larger than usual‐type leiomyomas (median maximum diameter, 82.5 mm vs 70.0 mm; P < 0.001) and more frequently exhibited cystic areas (33.2% vs 12.8%; P < 0.001). Acoustic shadows were present in 79.1% of variants, compared with 90.4% in usual‐type leiomyomas (P < 0.001). Some variant subtypes appeared only in premenopausal women and had distinct morphological characteristics. Epithelioid leiomyomas were the largest variant, with a median diameter of 139.5 mm. Mitotically active leiomyomas showed regular margins and uniform echostructure, and lacked cystic areas in almost all cases. Lipoleiomyomas contained calcifications in some cases. After reviewing the ultrasound images, 13 patterns were identified, some of which were distinctive of specific variant subtypes. Conclusion Patients with usual‐type vs variant leiomyomas presented with some distinct clinical and ultrasound characteristics. Among variants of leiomyomas, some histotypes exhibited distinctive clinical and ultrasound features. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.