Benign metastasizing leiomyoma: a systematic review of diagnosis, management, and outcomes

BACKGROUND: Benign metastasizing leiomyoma (BML) is a rare complication of uterine fibroids, in which benign smooth muscle tumors spread to distant sites. Due to its rarity, clinical presentation and management remain insufficiently defined. This systematic review provides a comprehensive overview of BML. This study aimed to assess the clinical characteristics, treatment methods, and outcomes of patients with BML. METHODS: The review included case reports and case series. A literature search was conducted in Google Scholar and PubMed using the keyword "benign metastasizing leiomyoma" from January 1, 2000 until March 31, 2024, yielding 310 articles from Google Scholar and 468 from PubMed. After removing duplicates and screening titles and abstracts, 213 articles were included. Data were systematically extracted on patient demographics, menopausal status, surgical history, tumor characteristics, imaging studies, histopathology, genetic tests, treatment methods and survival outcomes. RESULTS: The mean age was 47.8 years, and 89 (32.1%) patients were asymptomatic. The most common symptoms were: cough (n=55, 29.3%), dyspnea (n=52, 27.7%) and abdominal pain (n=42, 22.3%). Metastatic lesions were primarily found in the lungs (n=235, 84.8%), followed by the peritoneum (n=40, 14.4%), vertebrae (n=17, 6.1%) and heart (n=15, 5.4%). Total and subtotal hysterectomy was performed in 180 (75.3%) and 26 (10.9%) patients, respectively. The majority of patients (n=239, 86.3%) underwent surgery, performed before BML diagnosis in 200 cases (83.7%) and after diagnosis in 39 cases (16.3%). The mean time between surgery and the diagnosis of BML was 101 months. The most common positive receptor expressions were for estrogen (n=181, 65.3%), progesterone (n=178, 64.3%) and desmin (n=129, 46.6%). Adjuvant treatment included predominant use of hormonal agents (n=82, 29.6%), while chemotherapy was rare (n=3, 3.8%). The mean follow-up was 18 months. Among the eight patients (2.9%) who died from BML progression, the disease was the direct cause of death in three (37.5%) cases. CONCLUSIONS: BML is a rare complication of uterine fibroids characterized by frequent pulmonary metastases, hormone receptor positivity, and variable clinical course. Hormonal therapy is the mainstay of adjuvant treatment, but disease progression and death can occur, highlighting the importance of individualized management and follow-up.