Ampullary Amphicrine Carcinoma: A Rare Case Report With Review of Literature.

Neuroendocrine differentiation is a common feature observed in epithelial tumors. Both exocrine and neuroendocrine differentiation can be observed in tumors originating from the gastrointestinal system. However, since 1924, these tumors have been described under different names, leading to confusion among clinicians. While such tumorsare generally referred to as mixed adenocarcinoma-neuroendocrine carcinoma in the 4th WHO classification, amphicrine tumors are not currently included in any specific tumor classification. This study aimed to enhance the understanding of the clinicopathological features of amphicrine tumors, thus contributing to their standardized classification. A 52-year-old woman presented to our center with persistent nausea and vomiting. Physical examination revealed no findings except tenderness in the right upper quadrant of the abdomen. Intraoperative consultation revealed a tumor, approximately 8 mm in diameter, in the ampullary region. A tumor showing neuroendocrine differentiation was observed in the hematoxylin and eosin-stained sections. After formalin fixation, tumors with neuroendocrine differentiation were observed in the sections. Trabecular and glandular patterns, and nuclear salt-and-pepper chromatin were observed in the tumor cells. Immunohistochemically, the tumor cells were positive for synaptophysin and chromogranin. Alcian blue staining was positive for cytoplasmic mucin, and diffuse CDX2 expression was observed. As a result, the diagnosis was confirmed as "amphicrine carcinoma." Based on these findings, this type of tumor should be included as a separate histological type from adenocarcinomas, neuroendocrine carcinomas, and mixed neuroendocrine-nonneuroendocrine neoplasm. This will also support a more standardized approach in terms of the treatment and follow-up protocols for patients with this rare tumor.