Benign Metastasizing Leiomyomas to the Lungs: An Institutional Case Series and a Review of the Recent Literature.

BACKGROUND: Benign metastasizing leiomyomas (BMLs) represent the extrauterine spread of a benign uterine process. Pulmonary BMLs are the most common example of distant spread of uterine leiomyomas and are usually found incidentally in premenopausal women. The rarity of BMLs accounts for the limited literature that currently exists regarding their underlying pathophysiology, disease course, and management. METHODS: A retrospective analysis was performed of all BML cases diagnosed and managed at Brigham and Women's Hospital during a 22-year period. The demographic and clinical characteristics of these patients were compared with a PubMed-derived cohort of BML cases reported since 2006. RESULTS: Benign metastasizing leiomyoma tumors were identified in 10 Brigham and Women's Hospital patients, whereas 57 cases were reported in the literature. The average age at diagnosis was 54.1 and 46.7 years, respectively. Mean interval time from a pertinent gynecologic procedure to BML diagnosis was 23 years at Brigham and Women's Hospital. All patients demonstrated positivity for actin, desmin, and estrogen/progesterone receptors, confirming the diagnosis of uterine leiomyomas. Management primarily consisted of diagnostic resection with subsequent observation with or without hormonal suppression for residual pulmonary nodules. Progression of residual BMLs was noticed in 30% and 8.3% of Brigham and Women's Hospital and literature patients, respectively, when follow-up was reported. One patient in our series required further surgical management. CONCLUSIONS: Benign metastasizing leiomyomas are a rare cause of pulmonary nodules. They likely represent a clonal spread of uterine leiomyomas to the lungs. Management includes pathologic diagnosis with long-term surveillance with or without hormonal manipulation.