Today we discussed a case of a patient w/ probably pancreatic cancer, but who had previously had a whipple for a suspicious pancreatic head mass that turned out to be a IPMN, or intraductal papillary mucinous neoplasm of the pancreas.
These fall w/in the larger category of cystic neoplasms of the pancreas; IPMNs are not cancer per se but benign cystic neoplams that have the potential to become malignant. Gerald Hsu, our expert oncology discussant, led us on a brief discussion on evaluation and management.
IPMN were first described in 1982, after a small series of patients were thought to have “pancreatic adenocarcinoma” but had much better outcomes than usual. Their tumors were notable for being inside the pancreatic duct, large, and mucin-secreting. Typically we find them when imaging the abdomen for other reasons, and then, like the pulmonary nodule or adrenal mass, we have to follow them.
IPMN in the main pancreatic duct may have carcinoma in situ in up to 70% of identified tumors, unfortunately there are no imaging correlates that help evaluating risk of malignancy. In branch duct IPMN, Tumors greater than 3cm in size confer a higher risk of malignancy, and tumors less than 2 cm in diameter are rarely malignant.
The first step in evaluation is to define whether main duct or branch duct, and then figure out if the patients have symptoms or not. These can either be obstructive symptoms similar to those w/ pancreatic head masses (jaundice, LFT abnl), or pancreatitis. If no symptoms then it depends on duct size related to the tumor. For smaller lesions repeat imaging can be done, medium EUS/FNA, and big resection. Branch duct differs in that reseaction is considered for any symptomatic obstructions, for cysts >3cm or mural nodules within the wall of the pancreas.