Mucinous Tumors of the Exocrine Pancreas: Intraductal Mucin-Hypersecreting Neoplasms

Mucinous Tumors of the Exocrine Pancreas: Intraductal Mucin-Hypersecreting Neoplasms

IPMTs occur mostly in men in the sixth to seventh decade (range = 40 to 85 years). The most common presenting symptom is abdominal discomfort associated with mild elevations of pancreatic serum enzymes mimicking chronic or relapsing pancreatitis. The history of pancreatitis or recurrent pancreatitis varies from 29% [5] to 80% [8] in the literature. These symptoms are more commonly observed in patients with mucinhypersecreting tumors and are most likely due to intermittent obstruction of the main pancreatic duct by plugs of viscous mucin or intraluminal tumor. Back pain (25%), jaundice (25%), weight loss (42%), steator-rhea (37.5%), and diabetes (37.5%) are among various presentations reported in one series. [5] In a recent report from our institution describing outcomes of 25 patients with IPMTs, [9] 52% of patients had acute relapsing pancreatitis with elevated pancreatic enzymes, 32% had pain with normal enzymes, 12% had weight loss with no pain, and 4% had incidental findings. Therefore, due to the indolent nature of these tumors and the limited awareness of this lesion among the medical community, a delay in diagnosis ranging from months to years is not uncommon.

Conventional imaging studies such as abdominal CT scanning and transabdominal ultrasonography reveal nonspecific changes that are indistinguishable from those of chronic pancreatitis, pancreatic pseudo-cysts, or nonmucinous producing cystic neoplasms. These studies typically demonstrate well-defined unilocular or multilocular cystic pancreatic masses and/or dilatation of the main pancreatic duct. The term cystic duct here would be a misnomer since these cystic structures represent dilated ductular structures. The cystic changes of IPMTs may occasionally be so extensive as that they are confused with a mucinous cystic neoplasm. An important distinction between the two lesions is that, in IPMTs, the "cysts" communicate with the duct system, whereas MCNs generally do not show any connection with the duct system.