Transitional cell carcinoma metastasizing to an atrial myxoma.

Clinical Summary We present the case of a 75-year-old white man presenting with acute dyspnea, who was found to have a left atrial myxoma on transthoracic echocardiography. Before surgical intervention, the patient had nonspecific complaints of lethargy and felt generally quite unwell but had no other specific symptoms or clinical signs of malignancy, urologic or otherwise. At the operation, the tumor was excised through a transverse right atrial incision and sent for pathologic investigation. The patient was taken to the intensive treatment unit for postoperative respiratory support. Once conscious, he was noted to have a paralyzed left leg. Computed tomography of the abdomen and pelvis demonstrated ascites, atrophic kidneys, and widespread lymphadenopathy, which might have resulted in monoparesis of the left leg. Results of computed tomography of the head were normal. On histologic examination, the specimen consisted of a firm, well-circumscribed, gelatinous mass measuring 1.2 3.1 3.4 cm with features of a typical, albeit degenerate, atrial myxoma (Figure 1). In addition, there was evidence of metastatic carcinoma, with tumor cells within the vascular spaces and frequent mitoses (Figure 2). Glandular luminal openings were seen that were suggestive of adenocarcinoma or transitional cell carcinoma, and the results of immunohistochemistry were strongly positive for cytokeratin 7 and cytokeratin 20, thus suggesting the primary tumor was most likely a transitional cell carcinoma. Tumor markers for the thyroid, prostate, and lung were negative, but urine cytology was positive for malignant cells. Because of poor functional status and advanced disease, the patient was not considered to be suitable for radical chemotherapy or radiotherapy. Discussion Tumors of the heart are rare, with most being benign, of which myxomas are the most common. Malignant tumors of the heart are usually metastatic in origin, typically arising from the lung or breast, in lymphomas and with melanomas. Although most metastasizing tumors have been described with a varying incidence in the literature, it is extremely uncommon that cardiac metastases from transitional cell carcinoma are reported. The findings of metastatic tumor within the atrial myxoma was both unexpected and, in fact, very uncommon. It was only after the operation, when the patient experienced an unusual complication of left leg monoparesis, that further investigations revealed the extent of the advanced malignant process. Metastatic tumor deposits are not thought to be unusual in the heart at autopsy in patients with cancer (5%), but clinical manifestations are rare. We have found no other cases in the literature of metastatic tumor within an atrial myxoma, only cases of metastases mimicking myxoma. From St Thomas’ Hospital, London United Kingdom.