We report on a 74-year-old female patient who was admitted to the hospital because of abdominal pain. She underwent a colonoscopy and a stenosing mass was found in the cecum. Histologic findings in the biopsy specimens were consistent with ischemic colitis. Due to clinical symptoms and the endoscopic and radiologic findings that roused the suspicion that the patient was suffering from a malignant tumor, a right hemicolectomy was performed. Histology of the resection specimen disclosed an inflammation of the veins. It was characterized by a predominantly lymphocytic infiltration of the vessels affecting the veins of the colonic wall and the mesentery. Furthermore, secondary thrombosis with focal venous occlusion was observed. The colon showed extensive ischemic colitis with focal transmural coagulation necrosis. The disease was considered to be idiopathic lymphocytic phlebitis, which is a rare disease of unknown origin. Our patient is well and alive after more than 1 year, supporting the notion that the disease shows a benign course after surgery.