Simultaneous occurrence of pancreatic mixed acinar-ductal adenocarcinoma and primary follicular lymphoma of the duodenum, accompanied by increased number of IgG4 plasma cells in tumor-free parenchyma as concomitant IgG4-related disease or reaction to tumor? A case report.

Mixed acinar-ductal carcinoma is rare among pancreatic cancers, as is duodenal involvement in follicular lymphoma (FL). Although usually a systemic disease, primary FL of the duodenum occurs, with superficial involvement of the intestinal wall and low risk of progression. We report on a unique case of mixed ductal-acinar carcinoma of the pancreatic head accompanied by low-grade duodenal FL and autoimmune pancreatitis-like changes in adjacent pancreatic parenchyma. To our knowledge this is the first report of concomitant pancreatic mixed acinar-ductal carcinoma and duodenal FL. Clinico-pathological features of this unusual case, possible relationship between the entities and differential diagnosis are discussed.