A 45-year-old man was admitted to our hospital because of disseminated intravascular coagulation syndrome (DIC) and severe pain in his back and lumbar. Abdominal CT scan demonstrated lymph node enlargement in the whole body. FDG-PET revealed abnormal uptake of FDG in the thickening wall of the descending colon and the entire skeleton. Colonoscopy was performed continuously and revealed a poorly-differentiated adenocarcinoma of the descending colon. He was treated with the systemic chemotherapy of modified FOLFOX6 (mFOLFOX6). After one course of the treatment, DIC was resolved and severe back pain and lumbargo were improved.