Ampullary cancers are rare accounting for 0.2% of all gastrointestinal cancers. Signet ring is a rare variant of adenocarcinoma, characterized by having more than 50% of mucin secreting cells and clinically having a worse prognosis. We present the case of a teenage girl with this tumor, the youngest ever reported in medical literature. An 18 years old girl with no significant past medical history presented to our clinic with symptoms of upper abdominal pain and jaundice. Her upper GI endoscopy showed an ampullary lesion which was biopsied-diagnosing it as adenocarcinoma. She underwent a pancreato-duodenectomy (Whipple's procedure) with Child's reconstruction and a feeding jejunostomy. Her final histopathology report was documented as infiltrating adenocarcinoma of Signet Ring variety arising from the Ampulla of Vater. Being such a rare entity, there is a lack of randomized trials advising the optimum treatment for such cases. Till then anecdotal experiences will drive the optimum management of this rare disease.