A case of pulmonary benign metastasizing leiomyoma: clinicopathologic, immunohistochemical, and PET/CT analyses.

The pulmonary benign metastasizing leiomyoma (BML) is an extremely rare disease case, of which the pathogenesis was not elucidated. The accumulation of additional case reports and analyses is needed. A case of pulmonary BML is presented. A 48-year-old asymptomatic female patient that underwent a hysteromyomectomy 11 years ago was found to have abnormal shadows on a chest X-ray during a regular health check-up in 2012. Multiple nodular was observed in both lungs and uterine under computed tomography (CT) examination. Transbronchial lung biopsy surgery with a resection of the lesion was performed. The results revealed the pulmonary nodule was formed by benign smooth muscle cells which displayed very low mitotic activity. The samples showed highly positive signals for α-smooth muscle actin (αSMA), Desmin and Vimentin. Estrogen receptor (ER) and progesterone receptor (PR) were also immunoreactive positive. HMB-45, CD117 (C-kit) and S-100 were found to be negative with low Ki-67 index in the tumor cells. The pathological diagnosis was pulmonary BML. A total hysterectomy with adnexectomy were performed for the multiple uterine leiomyomas and pulmonary BML one week after diagnosis was made. From then on, the pulmonary nodules in both lungs were stable in 7 years postoperation, based on chest CT scan. When a solitary lung nodule is detected in a patient with a history of uterine leiomyoma, as an option, pulmonary BML, accurately diagnosing and proper treatment to has important implications for clinical outcome.