Heterotopic Hepatic Polyp Identified in the Right Atrium

Abstract

Heterotopic liver tissue has been described in the literature, more commonly observed in the abdominal cavity than in the thoracic cavity. In most reported supradiaphragmatic ectopic liver cases, there was a pedicle passing through the diaphragm and connecting the liver with the ectopic tissue. We report a case of heterotopic liver tissue misdiagnosed preoperatively as atrial myxoma. A 40 yearold woman presented to the Emergency Department with recurrent acute nocturnal respiratory distress. Transthoracic echocardiogram revealed a 2 x 2.5 cm floating mass in right atrium at the junction of inferior vena cava. The patient underwent sternotomy for resection of the atrial mass based on presumed diagnosis of cardiac myxoma. Pathologic examination demonstrated polypoid encapsulated benign hepatic tissue. We presented this case because it is an extremely rare condition that is commonly misdiagnosed, and is the second case to date, to the best of our knowledge, of supradiaphragmatic heterotopic liver polyp identified inside the cardiac chambers in a living adult person.

Ectopic Liver Tissue Presenting as a Right Atrial Mass on Echocardiography

“…Therefore, the authors of that case report proposed a theory that there can be hematogenous migration of hepatic cells with regenerative abilities even after intrauterine development. 6 Our case, along with the other reported cases with discrete intracardiac heterotopic masses without connecting stalks, 1 , 4 , 5 , 6 could be consistent with either premise, as all these reports noted right atrial masses. To our knowledge, there are no reports of intracardiac ectopic hepatic tissue in the left heart chambers.…”

“…It is hypothesized that it arises from a congenital defect of the septum transversum, embryonic tissue that differentiates into both the diaphragm and ventral mesentery of the foregut. 1 However, there is at least one reported case of the de novo development of an intracardiac ectopic liver mass. 4 The patient in that case had no evidence of the mass on surface echocardiography done 18 months before her presentation.…”

“…Only five cases of intracardiac involvement in adults have been reported to our knowledge. 1 , 3 , 4 , 5 , 6 One of the five cases was discovered incidentally postmortem, 3 and four of the five described a discrete mass without an anatomic connection to the liver. 1 , 4 , 5 , 6 …”

“…Ectopic liver tissue is a rare phenomenon that may have clinical implications ranging from local mechanical complications to malignant transformation. 1 The vast majority of reported cases of ectopic liver are intra-abdominal, 2 while most intrathoracic cases are extracardiac. Only five cases of intracardiac involvement in adults have been reported to our knowledge.…”

Surgical excision of ectopic hepatic tissue in the right atrium

“…In all cases of intracardiac/caval heterotropic liver tissue, the intervention of choice has been surgical excision via sternotomy and CPB. [3][4][5] Should the mass be positioned in such a way that hinders adequate flows on CPB, an alternative operative approach with deep hypothermic circulatory arrest may be used.…”