Mucinous adenocarcinoma occurs in 1.6-25.4% of patients with colorectal cancer. We report a case of a 27-year-old man with negative findings on initial colonoscopic biopsy, but finally diagnosed with mucinous adenocarcinoma of the colon. After undergoing an abdominal CT due to persistent abdominal pain, he was transferred to our hospital. The abdominal CT showed a diffuse and irregular wall thickening in the distal transverse colon. Due to the edema and stenosis of colonic wall, it was difficult to insert the colonoscope into the proximal region; a biopsy revealed chronic colitis with lymphofollicular hyperplasia. Transverse colectomy and lymph node dissection were performed. The diagnosis was mucinous adenocarcinoma of approximately 20×4.5 cm. Compared to adenocarcinoma, mucinous adenocarcinoma is found in a younger population with an advanced stage and is less responsive to palliative chemotherapy. Therefore, recalcitrant abdominal pain even in young people warrants early detection through appropriate examinations such as abdominal CT and colonoscopy.

Keywords: Adenocarcinoma, Mucinous, Colorectal cancer, Chemotherapy