A CASE OF INTRAMUCOSAL COLORECTAL CANCER WITH SESSILE SERRATED ADENOMA/POLYP DIAGNOSED BY MAGNIFYING ENDOSCOPY

Abstract

A 79-year-old man underwent colonoscopy for follow-up of colon adenoma. Conventional endoscopic view and chromoendoscopic view with indigo carmine dye showed a slightly reddish, protruded lesion, 3 mm in diameter, and a surrounding flat elevated lesion, 35 mm in diameter, with a mucous cap. Narrow band imaging with magnifying endoscopic view showed a surface pattern that was vague and irregular microvessel features in the protruded lesion and a regular surface pattern and regular microvessel features in the flat elevated lesion. Magnifying chromoendoscopic view with crystal violet staining showed an irregular tubular pit in the protruded lesion and a regular open-oval pit in the flat elevated lesion. We made the diagnosis of cancer with serrated lesion and performed endoscopic submucosal dissection. Histopathologic cross-section revealed well-differentiated tubular adenocarcinoma in the protruded lesion, and serrated lesion with irregular branching crypt and crypt dilation in the flat elevated lesion. The histological diagnosis was intramucosal colorectal cancer in sessile serrated adenoma/polyp (SSA/P). This case suggests that magnifying chromoendoscopy and NBI endoscopy are useful methods for diagnosis of colorectal cancer with SSA/P.