A Rare Case of Metastatic Colon Cancer Involving the Right Atrium Presenting as Superior Vena Cava Syndrome

Abstract

Colorectal cancer is one of the most common forms of malignancies and is well documented to metastasize to liver, lungs and peritoneum. Only a handful of well-documented cases of colorectal cancer metastasis to the right atrium have been documented. As such, we report a rare case of colon adenocarcinoma that metastasized to the right atrium and resulted in superior vena cava (SVC) syndrome. The patient is a 50-year-old male with history of hyperlipidemia, anxiety and metastatic colon cancer involving lungs and liver previously treated with chemotherapy and recently with immunotherapy who was transferred to our hospital for management of occluded SVC with the mass extending into the left atrium. The patient initially presented at another hospital for facial and upper extremity swelling and shortness of breath. A CT of the chest noted occluded SVC with a right atrial mass. This was further confirmed on transesophageal echocardiography which noted a large mass occupying most of the right atrial cavity measuring 6.8cm x 4.6cm and was noted to prolapse across the tricuspid valve in to the right ventricle. He was started on Eliquis and was transferred to our hospital for further management. He underwent an angiovac thrombectomy with Interventional Radiology (IR). During the procedure, findings of right atrial mass extending into the SVC were noted with subsequent partial debulking of the mass. Post procedure, the patient reported moderated improvement of his symptoms of dyspnea and swelling. Microscopic pathologic examination of the excised mass exhibited histomorphological features of metastatic colorectal cancer as cells demonstrated strong and diffuse nuclear reactivity for CDX2 stain. CT surgery evaluated patient for further surgical evaluation of right atrial mass, however he was deemed a poor surgical candidate. As such, IR placed a stent in the SVC to further alleviate SVC occlusion. Prior to discharge, Oncology also evaluated patient and recommend continued palliative radiation as outpatient. Conclusion: Although rare, any patient with a history of colorectal adenocarcinoma who presents with cardiopulmonary symptoms and suspicious cardiac mass should undergo evaluation for possible cardiac metastasis. It is recommended that a multidisciplinary approach involving cardiologists, oncologists, IR, and cardiothoracic surgeons is essential for determining the optimal therapeutic regimen for such patients.1483_A Figure 1. CT of the chest exhibiting the Right atrial mass1483_B Figure 2. Right atrial mass and thrombus extending into superior vena cava1483_C Figure 3. Microscopic pathologic examination of the excised mass exhibited histomorphological features of metastatic colorectal cancer as cells demonstrated strong and diffuse nuclear reactivity for CDX2 stain