Metastatic colorectal carcinoma to the right atrium: a case report and review of the literature.

Background: Cardiac metastasis due to colon cancer is extraordinarily uncommon. Given the rarity of diagnosis, there is paucity of evidence and hence, no established guidelines for evaluation or clinical management strategy.

Clinical Presentation: We present the case of a 59 year old male with a previously treated colonic carcinoma who presented with new onset exertional dyspnea. He was noted to be having a right atrial mass on an echocardiogram performed at his cardiologist's office. Further workup with CT angiogram of the chest confirmed a right atrial mass measuring 4.0 cm. Serum CEA was normal. Biopsies of the right atrial mass demonstrated metastatic moderately differentiated colonic adenocarcinoma. Mismatch repair protein expression analysis by immunohistochemistry showed no loss of MLH1, MSH2, MSH6 or PMS2 expression. Next generation sequencing for RAS and BRAF mutations was negative. Patient received treatment with FOLFIRINOX/ bevacizumab with noted reduction in size of mass.

Conclusion: To the best of our knowledge, this is the first report of next generation sequencing results available on a biopsy of metastatic colorectal cancer to the heart with the largest literature review of 31 reported cases of metastatic colorectal cancer to the heart. It will help direct clinical management and also adds evidence to the potential efficacy of treatment of this rare aggressive disease with chemotherapy in combination with VEGF inhibitors.