Abstract
Most physicians assume a pancreatic head mass with the double duct sign seen on imaging is adenocarcinoma until proven otherwise. An interesting and rare exception to this is the Primary Pancreatic Lymphoma (PPL), which accounts for only 0.5% of all diagnosed pancreatic masses. By recognizing some key cross-sectional imaging characteristics, early identification of PPL could be possible. A 54-year-old female presented to the emergency department with 2 weeks of progressive abdominal pain. Physical exam noted scleral icterus and epigastric tenderness. Labs demonstrated ALT 1,077 U/L, AST 798 U/L, total bilirubin 3.5 mg/dL, and lipase 622 U/L. The diagnosis of acute biliary pancreatitis was made. An abdominal US and CT were performed, which showed an uncinate process mass with central necrosis measuring 6.8 x 2.9 x 3.8 cm. The CBD was dilated to 10 mm with abrupt tapering of the distal duct. The pancreatic duct was mildly dilated to 3.5 mm. Also noted was a large irregular superior mesenteric lymph node measuring 11 x 6 cm which appeared to be continuous with the pancreatic mass. Despite extensive lymphadenopathy the mesenteric vessels appeared relatively normal. The pancreatic mass and lymph node were biopsied via EUS which showed diffuse large B cell lymphoma. An ERCP was performed for biliary decompression. Bone marrow biopsy revealed no lymphoma. Patient was started on R-CHOP therapy and responded well. She is now back to her baseline. Given its extremely low incidence, PPL is poorly understood. One review of the Surveillance, Epidemiology, and End Results database only identified 523 cases from 1973 to 2007. Most patients present similarly to the case described above. The key differences between PPL and pancreatic adenocarcinoma are a larger tumor size, lack of significant pancreatic duct dilation, and normal serum tumor markers. Imaging of the abdomen also reveals significant difference between PPL and adenocarcinoma, with PPL frequently demonstrating the sandwich sign, when a mesenteric mass appears as lymphadenopathy surrounding both sides of the mesenteric vessels, which remain spared. While the sign itself is not specific to PPL, it is specific for mesenteric lymphomas, and with pancreatic involvement, PPL should be considered. Recognition of these characteristic findings is important, as PPL carries a significantly different prognosis from other pancreatic malignancies and typically responds well to