Malignant melanoma of unknown primary origin presenting as cardiac metastasis

Abstract

Malignant melanoma has a very high propensity to metastasize to the heart. However, melanoma may sometimes present as a metastatic lesion in the absence of a primary lesion, which are called melanomas of unknown primary origin. We report a case in which a patient presented with a metastatic maligant melanoma in the right atrium with pericardial effusion and without a primary origin.

Keywords: Heart neoplasms; Melanoma; Neoplasma, unknown primary; Unknown primary.

Fig. 1

Chest computed tomography. An inhomogeneous enhancing mass in the right atrium (arrow) and a massive amount of pericardial effusion were identified.

Fig. 2

Two-dimensional cardiac echocardiogram. In a subcostal view of the heart, a large mass measuring 42×31 mm was visualized in the right atrium.

Fig. 3

Cardiac MRI. A large mass surrounding ascending aorta spread into transverse sinus and around pulmonary trunk and right pulmonary artery.

Fig. 4

Pathology and immunohistochemistry of the pericardial biopsy. A: cytoplasmic melanin-pigmented cells and prominent nucleoli were found (×200). B: in immunohistochemistry, antibodies to HMB45 were positive (×200).