Metastatic rectal cancer in the ampulla of Vater: A unique case

BACKGROUND: A metastatic lesion located in the ampulla of Vater is considered extremely rare, with only 32 cases reported globally. CASE: A 65‐year‐old patient was primarily diagnosed with a rectal adenocarcinoma. Twenty‐four months later as part of the oncological follow‐up, the patient was diagnosed with a single secondary tumor in the ampulla of Vater. After undergoing a pancreaticoduodenectomy (Whipple procedure), the patient experienced an uneventful recovery and received adjuvant chemotherapy. Sixteen months later the patient remained disease‐free. CONCLUSION: To the best of our knowledge, the present case represents the first reported metastatic tumor in the ampulla of Vater, originating from a rectal adenocarcinoma. This case underlines the critical role of immunohistochemistry in arriving at a correct diagnosis in order to guide clinical decision‐making.