Benign metastasizing leiomyoma.

A 41-year-old woman presented with chest pain and a cough. There was a solitary pulmonary nodule in the upper-left lobe. The patient had no history of neoplasm except a hysterectomy for uterine leiomyoma five years before. Six months after the first presentation, the tumor showed a gradual increase in size; an explorative thoracotomy was performed. The histopathologic examination showed a tumor consisting of well-differentiated spindle-shaped cells with intervening collagen. She was readmitted 8 months after the operation because of right-sided spontaneous pneumothorax. Multiple pulmonary nodules appeared when the lung was re-expanded by chest tube drainage. In conclusion, uterine leiomyomas can metastasize to various organs, such as lungs, despite having a benign pathologic appearance.