Elevated tumor-associated antigen CA 19-9 in a patient with an enlarged pancreas: does it always imply malignancy?

Carbohydrate antigen 19-9 (CA 19-9) has been used as a serum tumor marker for adenocarcinoma of the upper gastrointestinal tract, particularly primary adenocarcinoma of the pancreas. This tumor marker has also been used to differentiate benign from malignant diseases of the pancreas. However, significant elevations of CA 19-9 levels in the absence of pancreatic malignancy have also been reported. This case illustrates a marked elevation of CA 19-9 due to an infectious process in a patient with a pancreatic mass suggestive of malignancy.