Ampulla of Vater Undifferentiated Carcinoma

**Semantic type:** Neoplastic Process

**Definition:** An aggressive carcinoma arising from the ampulla of Vater. Morphologically, it is characterized by the presence of malignant epithelial cells without evidence of glandular or squamous differentiation. Signs and symptoms include jaundice, abdominal pain, anorexia, nausea, vomiting, and weight loss.