Intrapancreatic accessory spleen is a rare cause of pancreatic pseudotumors and is located in the pancreatic tail in approximately 1% to 2%. Accessory spleen itself is found in approximately 7% to 15% of the population. Our findings show a case of an intrapancreatic accessory spleen suspected for a malignancy in the pancreatic tail. A 63-year-old man admitted for cholecystitis was incidentally diagnosed with a tumor at the pancreatic tail. On hyperintense magnetic resonance imaging, a solid mass of 1.5 cm in diameter in the pancreatic tail was seen, which contrasted as hyperdense in T2-weighted imaging. Because of inhomogeneous enhancement on the early vascular phase, the diagnosis of a endocrine pancreatic tail carcinoma was suspected. Intraoperatively, an accessory spleen was found in the pancreatic tail. An oncologic left pancreatectomy was performed because of a malignant tumor. Histology showed an intrapancreatic accessory spleen in the pancreatic tail that excluded the presence of cancer. In conclusion, intrapancreatic accessory spleen is a rare cause of unnecessary laparotomy, but the absence of reliable diagnostics for this entity make histologic ascertainment of a benign tumor indispensable. Therefore, we still needed an oncologic tumor resection.