Background: The levels of carbohydrate antigen 19-9 (CA19-9) are often tested to stage pancreatobiliary tumours or to monitor the effects of treatment of such tumours. Benign diseases can also be associated with elevated CA 19-9 levels, but extreme elevation is rare in such cases.
Case description: An 84-year-old man was diagnosed with cholecystitis at the emergency department and received conservative treatment with antibiotics for this. After 5 weeks, the patient came to the outpatient clinic with unexplained icterus. Additional imaging revealed indications of malignancy and the CA19-9 concentration was 4240 kU/l. We suspected pancreatobiliary malignancy. However, ERCP revealed obstructive choledocholithiasis and we subsequently performed laparoscopic cholecystectomy. Based on histopathology examination of the gallbladder, a diagnosis of xanthogranulomatous cholecystitis was made. After surgery, CA19-9 levels decreased and the patient swiftly recovered.
Conclusion: Significantly elevated CA19-9 levels are not proof of pancreatobiliary malignancy. Our case underscores that CA19-9 is not an ideal tumour marker and that the results of CA19-9 tests should therefore be interpreted with some caution.