A case of MiNEN in the pancreatic head detected through medical examination

Abstract

The patient was a 72-year-old man. A blood test performed during his annual physical examination revealed a high CA19-9 level of 62.2 U/mL. As a CT scan revealed a tumor in the pancreatic head, he was referred to the hospital for further examination and treatment. A contrast-enhanced CT scan of his abdomen revealed a hypovascular tumor in the pancreatic head, which was suspected to be pancreatic cancer. An endoscopic ultrasonographic puncture aspiration biopsy was performed on the same area and the tumor was pathologically diagnosed as adenocarcinoma. Based on the procedure above, a diagnosis of pancreatic head cancer was made. The patient underwent a pancreaticoduodenectomy after preoperative chemotherapy. A histopathological examination of the surgical specimen revealed a honeycomb-like proliferation of poorly atypical cells with small round nuclei and pale sporangia. A poorly differentiated adenocarcinoma component was identified through hematoxylin eosin staining; both synaptophysin and chromogranin staining were shown to be positive through immunostaining. Part of the full-blown follicular structure was diagnosed as a neuroendocrine neoplasm. Since adenocarcinoma and neuroendocrine neoplasms were present in more than 30% of each other, the final diagnosis was primary mixed neuroendocrine-non-neuroendocrine neoplasm of the pancreatic head.