Abstract
Anaplastic carcinoma of the pancreas (ACP) is an aggressive pancreatic tumor that grows rapidly, and its clinical characteristics are poorly defined because of its rarity. Thus, preoperative diagnosis is difficult and most definitive diagnoses are generally made by surgery, highlighting the importance of collecting more cases of ACP. We report a case of a 79-year-old woman with ACP that was difficult to diagnose preoperatively. Abdominal enhanced computed tomography revealed a large and expansive tumor in the spleen containing multilocular cystic and solid components. The first preoperative diagnosis was splenic angiosarcoma, and the tumor could be resected by distal pancreatectomy, total gastrectomy and partial transverse colectomy. ACP was first diagnosed based on postoperative histopathological findings. ACP that spreads to the spleen and forms an intrasplenic mass is rare. However, ACP should be included in the differential diagnosis of such patients, and further research of ACP is essential for a favorable prognosis.