Metastasizing uterine leiomyoma. A case with cardiac and pulmonary metastasis.

A case of histologically benign cardiac and pulmonary metastases from a uterine leiomyoma in a 45-year-old woman is reported. The solitary cardiac tumor consisted of five lobules with a stalk attached to the anterior papillary muscle of the right ventricle, which occupied the right ventricular cavity and almost completely obstructed the pulmonary main trunk in the systolic cycle. Multiple small nodules were found throughout both lungs. The cardiac tumor was resected at open heart surgery and open lung biopsy of the pulmonary lesion was simultaneously performed. Both of them were histologically identical to the apparently histologically benign uterine leiomyoma which had been resected five years previously. Based on the clinical and laboratory findings, it is postulated that antegrade metastases via the venous system resulted in the cardiac metastasis from the uterine leiomyoma and the secondary pulmonary metastasis from the cardiac tumor. In contrast to the light microscopic findings, ultrastructural examination suggested the possibility of malignancy associated with the presence of immature smooth muscle cells. This is the first reported case of a so-called benign metastasizing leiomyoma occurring in the heart.