A Cardiac Tumor Traced to Merkel Cell Carcinoma

Clinicians report a unique patient case in which uncommon cardiac symptoms raised the suspicion and challenges of treating a rare cancer.


A patient with Merkel cell carcinoma (MCC) came to Sir Charles Gairdner Hospital in Perth, Australia, after 2 weeks of dyspnea. He was diagnosed with cardiac tamponade and received urgent pericardiocentesis. An echocardiogram and computer tomography scan showed a large infiltrating mass in the heart. Immunohistochemistry of the pericardial fluid revealed MCC. The MCC had metastasized to his heart—the tenth such reported case, and the second case reported of MCC causing cardiac tamponade.

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The clinicians report on several “important illustrative aspects” that appeared while they were unraveling the clues to the patient’s condition. One aspect was the challenge of the histopathologic diagnosis itself. The majority of patients with MCC present with localized disease, they note. Only 4% of patients have distant metastases, usually to lymph nodes, lung, central nervous system, and bone. MCC metastases to the heart are extremely rare. Most commonly, a cancer that spreads to the heart has started in the lungs, esophagus, or breast, or has begun as lymphoma, melanoma, or leukemia.  

However, it’s “exponentially more likely,” the clinicians say, for a cardiac tumor to be a metastasis than a primary cardiac tumor, and it is uncommon for the heart to be the only site of metastatic disease from a noncardiac malignancy. Thus, the patient represented a unique case: apart from an internal mammary lymph node, the heart was the only site of distant metastatic spread.  

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This patient’s case highlights the importance of early and accurate diagnosis of MCC with aggressive surgical treatment for localized disease, the clinicians say. New cardiac symptoms in the setting of malignancy should raise suspicion of cardiac metastasis.


Di Loreto M, Francis R. BMJ Case Rep. 2017. pii: bcr-2017-221311.
doi: 10.1136/bcr-2017-221311.

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