Autoimmune pancreatitis (AIP) resembles pancreatic carcinoma clinically and radiographically,and as such the diagnosis of autoimmune pancreatitis is challenging to make.
form of pancreatitis that was first described in 1995 and has more recently
been recognised as a manifestation of IgG4-RSD. It most commonly occurs in
older men. As it is commonly associated with a biliary stricture, AIP often
mimics pancreatic cancer presenting with painless jaundice, weight loss,
diabetes mellitus. Patients with AIP may have a focal mass or diffuse
pancreatic abnormality. In the USA, AIP has been reported to account for 2.5%
of all cases undergoing Whipple’s resection, and for up to 20-23% of those with
benign conditions1. AIP is commonly associated with sclerosing lesions in
many other organs. Only 44% of cases of AIP have
The most important
differentiation from AIP is pancreatic carcinoma. Features that are highly
suggestive of AIP over carcinoma are1: diffuse enlargement of the pancreas
with a capsule-like rim, and diffuse narrowing of the pancreatic duct. In AIP,
areas of restricted diffusion on MRI scan can be diffuse, solitary or multiple,
whereas pancreatic cancer typically shows only solitary abnormality. A serum
IgG4 level of more than 2.8 g/l is highly suggestive of AIP3.
PEt-CT has been suggested as an aid in differentiating AIP from pancreatic carcinoma4, 5 and in this case it was negative, i.e. did not show any significant metabolic activity in the pancreatic mass.