Pancreatic bronchogenic cyst: Easily hidden, difficult to identify

Abstract

Presenter: Prakash Jayanthi MD | Michigan State University College of Human Medicine Background: A bronchogenic cyst is a rare congenital anomaly, presenting as a cystic mass of nonfunctioning respiratory tissue. Retroperitoneal bronchogenic cysts are extremely rare, and present with non-specific symptoms, cloak themselves as other diseases, or can be an incidental finding on imaging. There have been less than 50 published cases of retroperitoneal bronchogenic cyst, and significantly fewer pancreatic bronchogenic cysts. Methods: A 72-year-old female presented originally to her local hospital with complaints of recurrent hematochezia. On CTA abdomen, a 7 cm cystic mass was incidentally discovered, contiguous with the pancreatic tail. She denied any history of pancreatitis, abdominal pain, weight loss, or other issues. She also denied any family history of pancreatitis, or other pancreas-related issues. She underwent an endoscopic ultrasound with fine needle aspiration. Biochemical analysis of the fluid showed an elevated Amylase of 4115 U/L, and a CEA of 2080 ng/ml. Due to these findings, the cystic lesion was thought to be an intraductal papillary mucinous neoplasm. Hence, the patient underwent a robotic distal pancreatectomy and splenectomy. Her post-operative course was uneventful, and she has recovered well since. Results: Macroscopically, the resected area measured 10.0 cm x 3.5 cm x 2.0 cm, and the cyst measured 8.6 cm x 6.0 cm x 4.5 cm, gray to brown-red in color and encapsulated. The specimen when sectioned revealed a unilocular cyst containing brown to gray-green, inspissated, mucoid material that was turbid. Inner lining of the cyst was pale tan, focally red, and smooth, with a 0.1cm thick wall. The lesion was noted to be adjacent to the superior edge of the resected pancreas, and did not involve the pancreatic duct. Microscopically, the cyst lining consisted of a single layer of benign pseudostratified ciliated respiratory-type epithelium. The cyst wall contained smooth muscle and focal cartilage. The cyst was intact, and did not communicate with the pancreas. As per pathology, this was consistent with bronchogenic cyst, rarely reported in this anatomic location. Conclusion: Bronchogenic cysts arise from the endodermal foregut. Buds from developing tracheobronchial tree often break off and migrate. These buds usually deposit in the area of the bronchus, commonly in pulmonary parenchyma and mediastinum. However, extremely rarely, the buds may migrate into the abdomen. As the bud must migrate before the diaphragm forms, abdominal cysts are extremely rare; not many cases have have been identified and described. Histologically, a psuedostratified ciliated lining, with cartilage or seromucinous glands or both, are necessary for a diagnosis. Reports of other elevated markers on biochemical analysis, including CA-125 and CA-19-9, and also CEA and amylase as in this case. Diagnostic imaging of the cyst seems better performed by MRI, as it allows for ruling out other causes of embryonic cysts, such as teratomas and dermoid cysts, from the differential diagnosis. The usual course of treatment for these cysts is surgical resection.