A Pancreatic Head Mass and Extreme Elevation of CA 19-9; a Benign Masquerade of Cholangiocarcinoma

Abstract

Background: Carbohydrate antigen 19-9 (CA 19-9) is a specific tumour marker for pancreatic and biliary malignancy. Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated condition in which IgG4 infiltrates are found in various organs, including the biliary tract and can present as pseudotumours. Method: This case report describes of an extreme elevation of CA 19-9 level of 3295 kU/L, in an 83-year-old woman presenting with severe obstructive jaundice and weight loss. An MRCP revealed a mass at the head of pancreas, amputating the biliary tree. Liver function tests revealed a significant cholestatic pattern and severe hyperbilirubinaemia (289umol/L). IgG4 level was found to be elevated 7.97g/L (normal titres 0.04-0.86g/L). Treatment high dose corticosteroids were commenced. Two months later a repeat MRCP revealed complete disappearance of the pancreatic head mass. There was also normalisation of the bilirubin and a dramatic decrease of CA 19-9 to 154 kU/L. Results: This case reports the highest published benign elevation of Ca19.9 level in the setting of IgG4 disease. In IgG4-RD, IgG4 histopathologic infiltrates are found in various organs. Immunoglobulin G4 sclerosing cholangitis and associated pseudotumours, biliary manifestations of IgG4-RD, are a recently described disease processes. Complicating diagnosis of IgG4-RD is the potential for dual pathology in patients; that being the presence of both cholangiocarcinoma as well as IgG4-RD. Conclusion: Differentiation between cholangiocarcinoma and IgG4-RD is extremely important, as the treatment is vastly different. This case illustrates that extreme elevation of Ca19.9 cannot be equated with malignant diagnosis in the setting of IgG4 disease.