An Uncommon Cause of Posterior Mediastinal Abscess.

SESSION TYPE: Infectious Disease Cases IPRESENTED ON: Monday, October 22, 2012 at 01:45 PM - 03:00 PMINTRODUCTION: Posterior mediastinal abscesses are caused commonly by iatrogenic esophageal perforation and descending oropharyngeal infections. It rarely arises from below the diaphragm. Pancreatitis may extend into the mediastinum and manifest as mediastinitis, abscess or pseudocyst.CASE PRESENTATION: Patient is a 66-year-old female with recurrent pancreatitis necessitating four hospitalizations in one year. It was complicated by multiple pseudocysts on the body and tail of her pancreas, with development of necrosis at the tail. Transgastric pseudocyst drainage with stenting was not feasible. She was repeatedly treated with broad spectrum antibiotics. Four months later, she was readmitted to ICU with sepsis, acute kidney injury and hypoxic respiratory failure. She developed new bilateral pleural effusions. Blood cultures were negative. Sputum culture showed Klebsiella pneumoniae and Stenotrophomonas maltophilia. She was treated with vancomycin, cefepime and metronidazole. Abdominopelvic CT imaging showed atrophy of the pancreas with a hypodense lesion along the anterior aspect of the body of the pancreas and a soft tissue density abutting the distal esophagus in the lower mediastinum measuring 4 x 3 cm, possibly a pseudocyst formation, given her history of pancreatitis. She succumbed to death with multi-organ failure and shock. Postmortem autopsy showed 5 cm purulent cavity in the posterior mediastinum that grew K. pneumoniae and S. maltophilia.DISCUSSION: Mediastinal extension of pancreatic pseudocyst with abscess formation is an uncommon complication of pancreatitis. It is caused by rupture of the pancreatic duct posteriorly into the retroperitoneal space with tracking of fluid to the posterior mediastinum through the esophageal (more common) or aortic hiatus. Its rupture into the pleural space produces pleural effusion which occur 53% of the time. The most common symptom is weight loss which is noted in 85% of patients, the others being dyspnea, chest pain, nausea, vomiting or dysphagia. Diagnosis is made on CT scan, which demonstrates a thick walled, cystic lesion in the posterior mediastinum. MRI is helpful in demonstrating fistulous tract extending from the pancreas. High amylase content from the cyst is confirmatory. Management includes endoscopic or surgical drainage. Spontaneous regression of mediastinal pseudocysts is rare.CONCLUSIONS: Pancreatic pseudocyst is a common complication of acute and chronic pancreatitis. Rarely, it may extend to mediastinum, which may pose a diagnostic and therapeutic challenge to the clinician. High index of suspicion facilitates appropriate therapy to reduce morbidity and mortality.1) Gupta, R. et al Mediastinal Pancreatic Pseudocyst, Medscape General Medicine 20072) Sadat, U. et al Mediastinal extension of a complicated pancreatic pseudocysts, Journal of Medical Case Reports 20073) Johnston, R., et al Pancreatic Pseudocyst of the Mediastinum, The Annals of Thoracic Surgery 1986DISCLOSURE: The following authors have nothing to disclose: Sheryll Soriano, Amardeep Shrestha, Mingchen SongNo Product/Research Disclosure Information, Springfield, IL.