Benign metastasizing leiomyomatosis: case report and review

The authors report an interesting case of a minimally symptomatic 23-year-old African American woman who was found to have extensive diffuse reticulonodular opacities of the lungs on a routine chest radiograph. She had a hysterectomy 5 years previously for multiple leiomyomas of the uterus. She had no history of any prior exposure to dusts or toxins. Collagen vasculitides and bacterial, mycobacterial, and fungal infectious causes were excluded through standard testing, and a bronchoscopic lung biopsy was nonspecific. An open lung biopsy revealed multiple nodules of proliferating smooth muscle cells intermixed with irregular areas of epithelial-lined spaces. Histologically, the muscle cells appear benign with a very low mitotic rate, and the pathologic findings were consistent with benign metastasizing leiomyomatosis (BML). Staining for estrogen and progesterone receptors, actin, and c-kit were performed. This case and the review of the medical literature support the concept that BML originates from an antecedent leiomyoma of the uterus in virtually all cases with rare exceptions. It appears that tumor metastasizes to lungs or other extrauterine tissues via hematogenous spread. However, the origin of the tumor remains controversial. BML is a rare entity, with only a handful of reports in the medical literature. The authors report an interesting case of BML in a 23-year-old patient who, to their knowledge, is the youngest such patient described and who, at 13 years, has the longest period of clinical follow-up. In this article, the authors review the pathogenesis, cytogenetics, histologic markers, and management options of this rare entity.