Communicating intrathoracic hydrocele.

Tense ascites may cause herniation of parietal peritoneal reflection into the mediastinum at the gastroesophageal junction. This may produce a mass visible on chest radiograph and computed tomography (CT). This communicating intrathoracic hydrocele may occur in the absence of hiatal hernia and may be confused with other middle mediastinal fluid collections including necrotic tumor, abscess, cyst of foregut origin, or pancreatic pseudocyst. Recognition of this entity in patients with ascites should prevent diagnostic confusion and unnecessary further evaluation.