Atrial fibrillation and tumor emboli as manifestations of metastatic leiomyosarcoma to the heart and lung

Leiomyosarcoma is a malignant tumor of the smooth muscle that rarely occurs in the gastrointestinal tract. High-grade leiomyosarcomas of the rectosigmoid usually metastasize to the liver and lungs. Although it is unusual, metastases to the heart have been reported. When this occurs, the metastatic tumor usually seeds in the right atrium and pulmonary artery. We report on and discuss a patient who had atrial fibrillation, peripheral emboli, and thrombocytopenia resulting from a low-grade rectosigmoid leiomyosarcoma metastatic to the pulmonary vein and left atrium. Atrial fibrillation is not a common manifestation of malignant neoplasms that have spread to the heart. Surgical removal of the tumor terminated the arrhythmia and thrombocytopenia.