Cancer Genes Mutations in Benign Metastasizing Leiomyoma: A Case Report.

Benign metastasizing leiomyoma is a very uncommon clinicopathologic entity with unknown molecular pathogenesis. We present a case of a 40-year-old woman who has a history of surgical resection of a large uterine leiomyoma and then subsequently presented with benign metastasizing leiomyomas to her lungs. Due to her tumor being estrogen receptor (ER) positive and progesterone receptor (PR) positive, she was empirically treated with anastrozole with sustained clinical benefit. Molecular studies with Foundation One testing showed low mutational burden and mutational variants in five known cancer genes. Our findings have important clinical and pathogenetic implication for metastasizing uterine leiomyoma.