by Jason Wasserman MD PhD FRCPC
February 3, 2023
Intracholecystic papillary neoplasm (ICPN) is a precancerous tumour in the gallbladder. If left untreated, ICPN can change into a type of invasive gallbladder cancer over time. For this reason, all ICPNs should be removed completely.
Right upper abdominal pain occurs in approximately half of all patients with ICPN. For the other half of all patients, the tumour is discovered incidentally when their gallbladder is removed for another condition such as chronic cholecystitis.
There are no known risk factors associated with ICPN. Unlike gallbladder cancer, gallstones (cholelithiasis) are not associated with an increased risk of developing ICPN.
When examined under the microscope, the tumour is made up of cells that resemble those normally found in the gallbladder, stomach, or colon. For that reason pathologists often describe ICPN as showing biliary (gallbladder), gastric (stomach), or intestinal (colon) differentiation. The pattern of growth is described as papillary when the cells connect to form long finger-like projections of tissue or tubular when they connect to form round or test tube-shaped structures.
All ICPNs show an abnormal pattern of growth called dysplasia. Dysplasia is important because it is a precancerous change that can become cancerous over time. When examining an ICPN, pathologists divide dysplasia into two levels: low grade dysplasia and high grade dysplasia.
Low grade dysplasia is an early precancerous change seen in most ICPNs. If left untreated, low grade dysplasia can change into high grade dysplasia or cancer over time. However, for most patients, the overall risk is low.
High grade dysplasia is a more advanced precancerous change seen in a small number of ICPNs. If left untreated, ICPNs with high grade dysplasia can turn into gallbladder cancer. For this reason, all ICPNs with high grade dysplasia should be removed completely.
A margin is any tissue that was cut by the surgeon in order to remove the tumour from your body. Dysplasia at the cut edge of the tissue means that the abnormal tissue may not have been completely removed from the body. For most patients, the entire gallbladder is removed among with the tumour. In this situation, the cut edges of the gallbladder will be examined carefully for dysplasia.