MUC5AC and Patent ductus arteriosus: The present case showed clinically aggressive scirrhous-type ascending colon cancer accompanied by locoregional and distant lymph node metastases at diagnosis and intrinsic chemosensitivity; this case was revealed to mainly consist of PDA but was not associated with extracellular accumulation of mucin or signet-ring cell components, except for a minute cluster in only a few lymphatic emboli in the surgical specimens of ascending colon tumors obtained after mFOLFOX6 plus cetuximab therapy.