A case of pancreatic mixed acinar-neuroendocrine carcinoma successfully diagnosed with endoscopic ultrasound-guided fine needle aspiration.

Mixed acinar-neuroendocrine carcinoma (MAEC) of the pancreas is a rare entity, and obtaining a preoperative diagnosis is difficult. We report a case of pancreatic MAEC successfully diagnosed with EUS-FNA. The case was a 72-year-old male with upper abdominal pain. Abdominal CT showed an irregular, hypovascular tumor of pancreatic tail. EUS-FNA was performed using a 22G needle. Immunostaining revealed positive results for the acinar marker trypsin and the neuroendocrine markers chromogranin A and synaptophysin. The possibility for MAEC was considered. He underwent distal pancreatectomy and splenectomy. Immunohistochemical examination of the tumor cells showed a wide range of positivity for bcl-10 and trypsin as well as for chromogranin A and synaptophysin, but negative results for CA19-9 and AFP. Considering that ≥ 30% tumors were positive for both acinar and neuroendocrine markers, the patient was diagnosed with MAEC.