Abstract: Pulmonary benign metastasizing leiomyoma：a case report and review of the literature　 Sun Daqiang , Zhang Xun , Han Qingliang ，Xu Feng Corresponding author：Zhang Xun , E-mail:zhangxun69@163.com Department of Thoracic Surgery , Chest clinical institute of Tianjin Medical University(Tianjin Chest Hospital) , Tianjin 300051 , China Abstract　Objective 　To highlight the characteristics of pulmonary benign metastasizing leiomyoma (PBML). Methods With a case report and review of the related literatures , the pathogenesis , clinical manifestations ,diagnosis , management and prognosis of pulmonary benign metastasizing leiomyoma were described. Results The pathogenesis of PBML remains controversial . The pathologic feature is that the tumor appears as interlacing bundles of smooth muscle cells and connective tissue , containing glandular appearing structures .Leiomyomas may undergo degenerative changes. There is few symptoms in most patients with PBML . Chest radiograph or computed tomography usually reveals multiple bilateral pulmonary nodules . PBML can be definitely diagnosed by histopathology and treated with pulmonary surgery and hormonal manipulation . The clinical course of PBML in most patients is benign. Conclusions 　Being rare and often misdiagnosed , PBML should be considered in patients showing multiple bilateral pulmonary nodules.

Key words: Lungneoplasms, Benign, metastasizing, Leiomyoma