[The clinical characteristics of pulmonary benign metastasizing leiomyoma]

Objective: Pulmonary benign metastasizing leiomyoma (PBML) is a rare entity that leiomyoma of uterus metastasized to the lung. The clinical characteristics of this rare disease were analyzed in this article. Methods: The detailed clinical records of 7 patients diagnosed as PBML at Peking Union Medical College Hospital between January 2001 and June 2015 were reviewed. Results: All patients were women with median age of 44 years (range 28-62). Symptoms included dyspnea (2/7), chest pain (1/7), cyanosis (1/7), cough (1/7) and bloody sputum (1/7), while 4/7 cases were asymptomatic. Six patients had the past-history of leiomyoma of uterus 20 months to 14 years ago among whom 5 patients received hysterectomy. Chest CT showed bilateral, random-distributed multiple round solid nodules, or diffuse-distributed miliary nodules, or single solid nodule, even some small cavities. Extra-pulmonary metastasis was found in left superclavicular lymph node (1 case) and right heart (1 case). Histological tissues were obtained by video-assisted thoracic surgery lung biopsy (4/7), mass resection on tricuspid valve (1/7), transbronchil lung biopsy (1/7), and CT-guided percutaneous lung biopsy (1/7). Pathology showed an interlacing pattern by spindle cells having elongated nuclei without cellular atypia. Ki-67 index was less than 1%. Molecules such as smooth muscle antibody, estrogen receptor (ER) and progestrone receptor (PR) were positive in immunohistochemistry staining. Neither letrozole nor zoladex was effective. Two patients responded to bilateral adnexectomy, presenting as shrunk nodules. No relapsed disease was seen in one patient with single nodule after resection. There was only one patient with disease-related mortality, whose chest CT showed milliary nodules. Conclusion: Although CT findings of PBML are similar to malignancies, the clinical outcome is good. Despite the positive expression of ER and PR, the effectiveness of hormone related treatment is limited. And periodical follow up is suggested even to those uneventful patients.