Intraductal pancreatic neuroendocrine tumor.

Intraductal lesions of the pancreas are usually due to intraductal papillary mucinous neoplasms and the less common intraductal tubular adenoma. Cases of acinar cell carcinoma within intraductal location have also been encountered recently. Pancreatic neuroendocrine tumors are rarely encountered within the main pancreatic duct. A 74-year-old male presented with non-specific abdominal symptoms and was found to have an obstructive lesion in the main pancreatic duct with associated chronic pancreatitis. A distal pancreatectomy was performed which revealed a solid and cystic tumor measuring 6 x 3 x 2 cm situated wholly within the main pancreatic duct. It formed an obstructing intraluminal polypoid lesion that resulted in surrounding chronic pancreatitis. Microscopic evaluation of the mass showed it to be a well-differentiated pancreatic neuroendocrine tumor with entrapped, non-malignant tubules. Intraductal pancreatic neuroendocrine tumors may occur in two settings. Firstly, and more commonly, there is a parenchymal-based tumor that then encroaches on and pushes into the main pancreatic duct. The less common scenario is of a primary intraductal location without a pancreatic parenchymal lesion. While an intraductal location of a pancreatic neuroendocrine tumor is rare, it should be borne in mind when confronted by an intraductal lesion in the pancreas.