This case report refers to a 31-year-old patient with an 11-year history of Crohn's disease. The patient presented with an edematous elevated lesion in the splenic flexure. Two histological analyses revealed no signs of obvious dysplasia, and the patient subsequently began infliximab treatment. Nine months later, a worsening of the stricture of the edematous elevated lesion was observed in the splenic flexure, and transverse colonic resection was performed. A histological investigation of the lesion in the splenic flexure revealed advanced adenocarcinoma. Six months after the surgery, computed tomography revealed recurrent carcinoma and peritoneal metastases. The patient was administered palliative chemotherapy.