[A case of serous cystic neoplasm with atypical imaging results suggestive of a prismatic internal structure].

The patient was a 67-year-old man with a 39-mm unilocular pancreatic tumor detected by computed tomography (CT). Further examinations with contrast-enhanced CT, magnetic resonance imaging, endoscopic ultrasonography, and endoscopic retrograde cholangiopancreatography revealed an internal heterogeneous structure attributed to bleeding or necrosis. Consequently, we expected either a pancreatic neuroendocrine tumor or a solid pseudopapillary neoplasm and performed pancreaticoduodenectomy. Pathological examination showed that the tumor had a denatured structure with evidence of internal bleeding and cubic epithelial cysts of various sizes. The final diagnosis was a macrocystic-type serous cystic neoplasm.