Primary cardiac tumors are rare, with atrial myxomas accounting for the vast majority of cases (1). These primary tumors are most often intracavitary, leading to obstruction and arrhythmias. In comparison to primary tumors, metastatic cardiac neoplasms occur more frequently (1, 2). However, the intracavitary growth of these tumors is less common, and therefore the patients may be asymptomatic and are only found to have cardiac involvement during post mortem examinations (1). Another entity that can mimic intracavitary cardiac mass is thrombus formation (2). Every malignant tumor in the body has the potential to metastasize to the heart, the commonest being malignant melanoma, carcinomas of the lung, breast, esophagus, angiosarcoma, lymphoma and leukemia (1-3). The pathways for spread of cardiac metastases include direct contiguous extension, lymphatic or hematogeneous spread and much less commonly through transvenous spreading. The lymphatic spreading of tumors usually appear in the form of pericardial metastases, while the hematogeneous spreading commonly gives rise to myocardial metastases (1). Tumor thrombus extension into the right atrium usually occurs via the transvenous route, from the SVC (thyroid, lung or thymic carcinomas) or IVC (Wilm’s tumor, renal, uterine or hepatocellular carcinomas) (1, 4-6). Review of the literature revealed no report of a case of thrombus involving th eright atrium extending to both SVC and IVC.. Our patient’s clinical presentation with progressive shortness of breath and facial and upper limb swelling is typical of superior vena cava involvement and right atrial congestion. Other presenting features of intra-atrial cardiac metastases include chest pain, hypotension, Kussmaul breathing and arrhythmias (1). In investigating a suspected cardiac mass, two-dimensional transthoracic or transesophageal echocardiography is usually considered the frontline investigation (1) as it is non-invasive, readily available and accurate in when performed by experienced specialists. Pericardial effusion, regional wall motion abnormalities, and intra-cavitary masses can be examined with high sensitivity. The next in line is CT, in particular an ECG-gated cardiac CT, as this would better delineate the intracardiac tumor and local extension, as well as evaluate adjacent structures. In our case, the extent of the thrombus was clearly depicted, and the neck and lungs were examined for primary tumors at the same session. Postoperative CT successfully detected the presence of left adrenal mass and small cystic liver foci suspicious of metastases, while the kidneys were deemed clear of masses. This has helped greatly in narrowing down the differential diagnoses of the primary tumor. Magnetic resonance imaging (MRI) also play a great role in investigating cardiac masses (1). However, this examination was not performed for our patient due to temporal and financial constraints. It is generally accepted that the incidence and progression of venous thrombosis in cancer patients are increased as compared to the general population, with 10% prevalence of occult malignancy after an episode of unexplained venous thrombosis (7). The increase in the risk of venous thrombosis in patients with malignancy is attributed to a hypercoagulability state, vessel wall damage and venous stasis. The composition of bland venous thrombus include platelet, red blood cells, fibrin and inflammatory cells, while the less common tumor thrombus also contains malignant tumor cells. The differentiation of venous from tumor thrombus is difficult, and more often is possible only by hepatic lesions examination. Several features on CT and MRI can be used to differentiate tumor thrombi from bland ones, the most characteristic feature being the enhancement of the thrombus aftern contrast administration, apart from expansion of the vessel lumen and heterogeneity of the thrombus (7, 8). The extent of massive thrombosis in our patient has prompted the suggestion to look for a primary malignancy, even before the histopathology result came back as malignant in nature. The presence of a left adrenal mass in our patient’s US and CT examinations has raised the possibility of adrenocortical carcinoma, as the primary tumor. As the venous drainage of the adrenals follows the kidneys’ pathway, adrenal tumors have the propensity to extend into the IVC. However, right atrial involvement in malignant adrenal tumors is very rare (5, 9, 10). It is worthwhile to note that while the histopathological examination may not ascertain the primary origin of the tumor thrombus, the cells were TTF-1 positive, increasing the possibility of occult lung adenocarcinoma. The CT scans on both occasions did not reveal the presence of mass lesions in the lungs. However, occult carcinomas could arise within the tuberculosis scars within the parenchyma. Lung carcinomas are also known to spread to the adrenal glands, which could account for the left adrenal mass in this patient. In conclusion, we present a case of a patient with right atrial tumor thrombus extending to both IVC and SVC, should be considered especially in the adrenal cortex or in the lung and liver deposits, suspicious of metastases. The histopathological examination of the thrombus revealed metastatic adenocarcinoma. This case highlighted that in patients presenting with extensive cavoatrial thrombus as presented, the existence of primary carcinoma should be considered especially in the adrenal cortex or in the lung.
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