S2735 Ectopic Hepatic Tissue Causing Mass Effect Presenting as Dysphagia

Abstract

INTRODUCTION: Ectopic hepatic tissue (EHT) located in the posterior mediastinum is rare. The etiology of EHT is not well understood. We present a case of posterior mediastinal EHT causing mass effect in a middle-aged woman presenting with dysphagia. CASE DESCRIPTION/METHODS: A 50-year-old female presented to the ED with one year of intermittent dysphagia. Described as a “ball-like” sensation in the epigastrium. She denied abdominal pain, nausea, vomiting, hematemesis, early satiety, anorexia or weight loss. Her medical history was significant for peptic ulcer disease. She denied history of abdominal trauma or family history of malignancy. She was hemodynamically stable. Initial labs were nonrevealing. Physical exam was unremarkable. CT chest revealed a well-circumscribed posterior mediastinal mass measuring 3.9 × 3.4 × 3.2 cm. The mass was located to the right of the esophagus, homogeneous and measured 40 Hounsfield units. Her liver was noted to have a similar attenuation coefficient. Endoscopic evaluation revealed an area of mild extrinsic compression at the distal third of the esophagus (35 cm) which was easily traversed by the adult EGD scope. The Z line was seen at 36 cm from the incisors. The posterior mediastinal lesion was noted from 32 to 35 cm. It had an echogenic appearance of hepatic tissue and was noted to be continuous with the left lobe of the liver. This lesion was surrounded by a capsule with well-defined endosonographic borders. The mass was adjacent to the descending aorta and the ventricle. Mediastinal EHT was suspected to be the etiology of her symptoms. Fine needle biopsy was not performed due to proximity to the left ventricle. No other abnormalities were identified. A liver-spleen scan confirmed hepatic tissue in the posterior mediastinum. Outpatient evaluation with cardiothoracic surgery was planned. DISCUSSION: Although typically benign, ectopic hepatic tissue still warrants surgical evaluation and resection. Beyond exerting mass effect on surrounding structures, EHT may also undergo a malignant transformation to hepatocellular carcinoma (HCC). A review of recent medical literature disclosed many cases in which EHT preceded development of HCC, even when the remainder of the liver did not have HCC. Further studies are needed to determine the rate of malignant transformation.We urge consideration of EHT as a differential in the evaluation of posterior mediastinal masses. Given EHT’s propensity for malignant transformation, early recognition and close follow up is of vital importance.Figure 1.: CT Chest demonstrating posterior mediastinal mass continuous with the left lobe of the liver.Figure 2.: Mild extrinsic compression at the distal third of the esophagus approximately 35 cm from the incisors.Figure 3.: Ectopic Hepatic Tissue in the mediastinum.