Marco Massani,1 Paola Maccatrozzo,1 Giovanni Morana,2 Luca Fabris,3 Cesare Ruffolo,1 Luca Bonariol,1 Bruno Pauletti,1 Nicolò Bassi1 1IV Department of Surgery, Regional Center for HPB Surgery, 2Diagnostic and Interventional Radiology, Regional Hospital of Treviso, Treviso, 3Molecular Medicine Department, University Hospital, Padua, Italy Introduction: Accessory spleen has a worldwide prevalence of 10%–30% and is defined as intrapancreatic accessory spleen (IPAS) when it locates within the pancreas. This occasional finding can raise difficulties in differential diagnosis with hypervascular pancreatic lesions, such as pancreatic neuroendocrine tumor. Presentation of cases: We present five cases in which a mass of the pancreatic tail was found on radiologic investigations. The first case was a young female patient who underwent a distal pancreatectomy because of a mass of the pancreatic tail misdiagnosed as a pancreatic neuroendocrine tumor due to its radiologic features on computed tomography and magnetic resonance imaging (MRI) (small, ovoidal, and well defined). Misdiagnosis also occurred in the second case, in which an 82-year-old woman was referred to our hospital because of a pancreatic mass of uncertain diagnosis. She also underwent an operation, and pathologic examination showed splenic parenchyma. A correct diagnosis was achieved in the remaining three cases that are still under radiologic monitoring. Discussion: IPAS is a benign entity and therefore does not require surgical treatment. We discuss the best diagnostic options that have recently been experienced, focusing on diffusion-weighted and superparamagnetic iron oxide MRI, which in our experience seem to be the safest and most easily accessible diagnostic tools. Conclusion: We suggest that a multidisciplinary approach should guide the diagnosis. When a pancreatic mass with specific features (round, ovoid, and well defined) is detected by computed tomography or MRI, an IPAS should be suspected. Keywords: intrapancreatic accessory spleen, superparamagnetic iron oxide, diffusion-weighted images, neuroendocrine tumor, neoplasm