Lymphangioma is a malformation of the lymphatic system, which can involve any part of the body. However, lymphangioma in the gastrointestinal tract is uncommon. Large intestine is the least commonly involved site. The authors encountered a case of lymphangioma mimicking neoplastic polyp located in the rectum of a 65-year-old woman on screening colonoscopy. The surface mucosa showed dark red. The vascular pattern was difficult to define on narrow-band imaging. This polyp was reckoned as a neoplastic polyp and endoscopic mucosal resection was performed. Histologic examination revealed lymphangioma accompanying pressure induced necrosis. This case indicates the possibility of misdiagnosis due to pressure necrosis of mucosa.