Atypical and uncommon CT and MR imaging presentations of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinomas (PDACs) occasionally have atypical and uncommon imaging presentations that can present a diagnostic dilemma and result in false interpretation. This article aimed to illustrate these CT and MR imaging findings, including isoattenuating PDAC, coexisting acute pancreatitis, PDAC with a cystic feature, groove PDAC, diffuse PDAC, hypointensity on diffusion-weighted imaging (DWI), multifocal PDAC, intratumoral calcification, and extrapancreatic invasion with a barely discernable mass. A subset of PDACs with atypical features are occasionally encountered during routine clinical practice. Knowledge of and attention to these atypical and uncommon variable imaging features may allow radiologists to avoid misinterpretation and a delayed diagnosis.