ampulla of vater small cell neuroendocrine carcinoma
An aggressive neuroendocrine carcinoma arising from the ampulla of Vater and the periampullary region. Morphologically, it is characterized by the presence of small malignant cells, necrosis, and a high mitotic rate. Signs and symptoms include jaundice, abdominal pain, anorexia, nausea, vomiting, and weight loss.