Ryo Maekawa

Novel Subtype Classification of Diffuse Uterine Leiomyomatosis Based on a Nationwide Survey in Japan

ABSTRACT Aim Diffuse uterine leiomyomatosis (DUL) is characterized by numerous uterine leiomyomas within and diffusely replacing the myometrium. However, because of its rarity, the prevalence, diagnostic criteria, and standard treatment for patients with DUL who wish to preserve their fertility remain unknown. This study aimed to clarify the current status of the diagnosis of DUL in Japan. Methods We conducted a web‐based survey targeting 1080 Obstetrics and Gynecology training institutions registered with the Japanese Medical Specialty Board. We asked them whether they had treated patients with DUL over the past 10 years (2013–2022). We obtained magnetic resonance imaging (MRI) scans from institutions that reported clinical experience with DUL, and conducted a central review to determine whether each case was consistent with DUL. We also investigated whether DUL could be classified into subtypes. Results Responses were obtained from 428 institutions, of which 128 reported clinical experience with DUL or DUL‐like multiple uterine leiomyomas, totaling 653 cases. MRI scans from 408 cases were centrally reviewed by a subcommittee, and 307 cases were confirmed as DUL. Based on the imaging characteristics, DUL was classified into three subtypes: total replacement, myometrial replacement, and submucosal‐dominant. Conclusions This survey revealed that 653 cases of DUL or DUL‐like multiple uterine leiomyomas were managed over a 10‐year period in Japan. Based on a central review of MRI scans, DUL can be classified into three distinct subtypes. Given the differences between these subtypes, treatment approaches for patients wishing to preserve fertility may vary, highlighting the need for further investigation.