Fig. 4. Grade 3 NEC in 41-year-old woman.

This patient was referred to our hospital with tentative diagnosis of ductal carcinoma of pancreas.

A. Magnetic resonance cholangiopancreatography showed abrupt tapering of intrapancreatic common bile duct with diffuse upstream dilatation. B. Contrast-enhanced CT showed 2.5-cm, relatively well-defined, low attenuating solid mass in head of pancreas. C. Tumor showed high FDG avidity on FDG-PET. Imaging reports suggested possibility of NEC as well as ductal adenocarcinoma of pancreas, indicating need for biopsy. D. H&E staining (× 40) revealed small, round, blue cells in tumor. Immunohistochemistry specimens (× 40) showed positivity on synaptophysin (E) and Ki-67 (F) staining with Ki-67 proliferation index of 70%. These findings confirmed diagnosis of NEC.