Metastatic malignant melanoma manifesting as an intracardiac mass

Antemortem diagnoses of intracardiac metastases are uncommon. Metastatic melanoma shows a propensity for cardiac involvement, but cardiac involvement by melanoma is rarely identified clinically due to a paucity of cardiac symptoms.

The surgical pathology files of Mayo Clinic were searched for cases of metastatic melanoma presenting or manifesting as an intracardiac mass. The lesions were evaluated pathologically for diagnoses. Clinical information was obtained by chart review.

Seven patients, four female and three male (age 31 to 79 years), were identified. No patient had a history of metastatic melanoma. All patients presented with dyspnea and symptoms of outflow obstruction. Echocardiography or CT revealed an intracardiac mass (four atrial, three ventricular). Six cases involved the right side of the heart and one involved the left ventricle. Five of the seven patients had a history of malignant melanoma, but none had a history of metastases when they presented with cardiac symptoms. In four cases, the history of primary melanoma was remote, occurring 7, 9, 13, and 28 years prior to the discovery of their cardiac mass. One patient had no history of melanoma, and no primary melanoma was ever identified. One patient had a history of a benign melanocytic lesion biopsied 2 years before, but retrospective review showed malignant melanoma.

Melanoma is known to have an unpredictable and prolonged course. Neoplastic involvement of the heart should be considered in patients with cardiac symptoms when a documented malignancy exists, no matter how remote.