Abstract
Duodenal metastases from pulmonary adenocarcinoma are rare. Early detection, diagnosis, and treatment are crucial for improving the prognosis of patients with duodenal metastases from primary lung cancer, which often go unnoticed due to their low incidence and diagnostic challenges. Here, we present the case of a 64-year-old man with an unusual occurrence of duodenal metastases from pulmonary adenocarcinoma, admitted with symptoms of cholangitis. Radiological findings revealed a mass in the D2-D3 segments of the duodenum. Endoscopic ultrasound with biopsy was performed, and immunohistochemical analysis confirmed that the mass was a duodenal metastasis of pulmonary adenocarcinoma.