INTRODUCTION: Pseudocysts are a common complication of both acute and particularly chronic pancreatitis. Uncommonly, pseudocysts may communicate with thoracic cavities, including the mediastinum. We describe a case of acute pancreatitis complicated by a mediastinal pseudocyst with bilateral pleural space involvement. CASE DESCRIPTION/METHODS: A 51-year-old male with a history of alcohol abuse presented shortly after discharge from a prolonged hospitalization for his first lifetime episode of acute alcohol-induced pancreatitis. A CT of the chest ordered on admission for new onset respiratory distress demonstrated bilateral pleural effusions. Fluid analysis showed a right sided empyema and left sided aseptic exudative effusion. The right empyema resolved after chest tube placement but there was rapid recrudescence of a right pleural effusion after chest tube removal. Repeat fluid analysis was significant for a pancreatic specific amylase level of 2620. Repeat CT imaging demonstrated a posterior mediastinal fluid collection that arose from the pancreas, extended through the esophageal hiatus and was contiguous with new fluid collections in both pleural spaces and this was confirmed with MRCP. The mediastinal pseudocyst was deemed not amenable to endoscopic drainage so ERCP was performed with stent placement to the ventral pancreatic duct along with chest tube placement for the larger right sided fluid collection and subcutaneous octreotide administration, with eventual reduction of pseudocyst size. DISCUSSION: Mediastinal pseudocysts are a rare complication of acute pancreatitis more commonly seen in chronic pancreatitis, though exceedingly rare in general. It is theorized that mediastinal pseudocysts occur based on ease of pancreatic fluid movement. The pararenal and pelvic extraperitoneal spaces are typically the easiest spaces for this fluid to penetrate but conditions that create inflammatory fibrosis of these areas may make ascending flow into the mediastinum the path of least resistance. On CT scan and on MRCP, our patient had a mediastinal pseudocyst that communicated directly and inseparably with both the right and left pleural space. To our knowledge, this has not been previously seen in the limited case reports of mediastinal pseudocysts. Despite not being amenable to endoscopic drainage based on location, the use of octreotide coupled with pancreatic duct stenting proved effective in reducing the caliber of this mediastinal pseudocyst on interval imaging.
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