Colonic metastasis from lung cancer is rare. The findings of metastatic lesion colonoscopies are variable, and such lesions usually have advanced features.Here, we report a case of a patient with lung adenocarcinoma metastasis to the colon presenting with chronic diarrhea. The patient underwent a colonoscopy, and a small depressed lesion was identified at the ascending colon. In narrowband imaging (NBI), the lesion appeared dark brown with an irregular and disrupted vascular pattern on the surface. An invasive tumor was suspected