Benign Metastasizing Leiomyoma: New insights into a rare disease with an obscure etiopathogenesis

Abstract

BACKGROUND: Benign metastasizing leiomyoma (BML) is a rare disease with an unknown etiopathogenesis that mostly affects middle-aged women with uterine leiomyoma. Many metastatic nodules outside the uterus characterize the condition. The metastases are smooth muscle lesions without malignancy. Morphologically and immunohistochemically, they resemble uterine leiomyomas, indicating a shared clonal origin. The lungs are the most prevalent site for incidental metastasis detection. BML has a relatively slow progression and good prognosis, and historically, there has been a lack of established guidelines for its treatment. CASE PRESENTATION: Herein, we report a case of BML in a patient with multiple metastases. Through extensive histological and immunohistochemical analyses, this complex case enabled not only the definitive diagnosis of BML, but also shed light on its complex etiopathogenesis. CONCLUSION: This study presents novel histology evidence suggesting a potential causal relationship between metaplasia and the development of BML.