Pulmonary metastases of a uterine smooth muscle tumor of uncertain malignant potential presenting as growing bullae: a case report.

Postoperative recurrences of uncertain malignant potential [(smooth muscle tumors of uncertain malignant potential (STUMPs)] have been reported, with lung as the most common site. Herein, we describe pulmonary metastases of a uterine STUMP presenting as bullae in a female patient. Computed tomography revealed two pulmonary metastases in the left lung with several bullae in both lungs, and the patient was referred to our department for pulmonary metastasectomy. Despite mild right pneumothorax on admission, left pulmonary metastasectomy and bullectomy were safely performed, with an uneventful postoperative course. Right pneumothorax recurred four days after discharge; hence, surgery was indicated. Although the air leak point was not a bulla but rather a pleural dissemination nodule, metastasectomy with bullectomy was performed. Pathological examination suggested that the bullae developed owing to retraction and collapse of the alveoli surrounding the pulmonary metastases. Bullae formed during the clinical course of malignancy have the potential of pulmonary metastases.