The Multifaceted Manifestations of Cardiac Tumors

Cardiac tumors, including the more common metastatic neoplasms and the less frequent primary tumors and tumorlike lesions, constitute an area of ongoing professional interest, and the topic has engendered considerable scientific literature seemingly out of proportion to the contribution of cardiac tumors to the totality of cardiovascular disease. Reasons for this phenomenon include the diagnostic and therapeutic challenges represented by cardiac tumors: the lesions frequently have perplexing presentations for clinicians, and they can elude clinical detection and become apparent as unexpected findings at cardiac surgery or autopsy.^1–7 As a result, a considerable body of knowledge has been developed in the medical literature regarding the pathology, natural history, diagnosis, medical therapy, surgical intervention, and clinical management of neoplasms and tumorlike conditions of the heart and great vessels.^1–11 Contemporary imaging methods, particularly echocardiography, computed tomography, and magnetic resonance, have added greatly to the likelihood of timely diagnosis of these lesions and to the application of targeted interventions for their treatment.^8–11 For the individual patient with a primary or metastatic cardiac tumor, application of this accumulated knowledge by an astute medical team can be life-saving.

Whereas contemporary knowledge of cardiac tumors is extensive, unusual manifestations of cardiac tumors continue to be seen and documented.^12,13 In this issue of the Texas Heart Institute Journal, Patel and colleagues¹⁴ have provided a well-studied and well-written case report and series review of metastatic colon cancer involving the right atrium. This report makes several cogent points regarding the contemporary diagnosis and management of cardiac tumors. The report documents the occurrence of an unusual pattern of cardiac involvement by tumor—in this case, a metastatic mucinous colonic carcinoma, with the tumor involving the right atrium and producing superior vena cava (SVC) syndrome and tumor emboli to the lungs and culminating in sudden death. Good correlation between the diagnostic imaging studies and histopathology is provided. The literature review documents 7 cases of right atrial involvement by metastatic colon carcinoma, but only this case has the unusual features of SVC obstruction and tumor emboli to the lungs.

Determination of the pattern of involvement of the heart and pericardium by mass lesions provides information important to the differential diagnosis of the cardiac condition (Fig. 1).² This determination can be made by diagnostic imaging, direct observation at surgery or autopsy, or both. Cardiac tumors can simulate or be simulated by nonneoplastic processes that produce space-occupying lesions. The pseudotumors include intracavitary thrombi or foreign bodies, intramural abscesses or hematomas, ventricular aneurysms, and coronary artery aneurysms. Histopathologic determination is crucial for definitive diagnosis of a mass lesion as a specific type of primary tumor, a secondary metastatic neoplasm, or a nonneoplastic process. Cystic lesions of the pericardium are typically benign lesions. Malignant lesions are more likely to produce pericardial adhesions, hemorrhagic pericardial effusion, or both. A solitary intramyocardial mass in the ventricular wall is likely to be a primary benign tumor. Multiple myocardial nodules are more likely to represent metastatic malignant neoplasia. An exception is rhabdomyoma, the most common cardiac tumor of infants and children, which may take the form of multiple nodules. With regard to atrial masses, benign myxomas typically are pedunculated lesions that are attached to the atrial wall by a thin stalk, as the bulk of the lesion projects into the atrial chamber. The most common site for myxomas is the left atrium, with the attachment site at the middle of the interatrial septum, although typically pedunculated myxomas also can arise in the right atrium. Sessile lesions with broad attachment to the atrial wall are more likely to be malignant tumors. In the current case,¹⁴ the mucinous colonic carcinoma produced a pedunculated mass in the right atrium, but the lesion was attached to the free wall of the right atrium rather than to the interatrial septum. This unusual location, coupled with the presence of multiple pulmonary nodules, raised a strong suspicion of metastatic disease. Gross and histopathologic findings at autopsy confirmed that the right atrial lesion was a thrombotic mass containing neoplastic cells associated with extension into the SVC and multiple tumor emboli.

Fig. 1 Patterns of involvement of the heart and pericardium by primary and secondary tumors. Reproduced by permission from: Buja LM. Cardiac tumors. In: Willerson JT, Sanders CA, editors. Clinical cardiology (the science and practice of clinical medicine). New York: Grune & Stratton; 1977. p. 400–4.

Patel and colleagues provide a cogent discussion of the diagnostic methods and surgical approaches for the detection and treatment of metastatic carcinoma with this type of cardiac involvement. A fairly recent literature review⁷ makes the case that cardiac involvement by metastatic disease has increased during the last 30 years. The primary cardiac lesions, although they usually show benign cytology, often occur in strategic locations, where they can cause substantial clinical complications without diagnosis and effective treatment. These considerations provide more than enough reasons for physicians to maintain a fascination with, and a high degree of suspicion for, cardiac tumors and their multifaceted manifestations.