Hematoxylin and eosin staining showed that most metastasized cancer cells had poorly differentiated morphology; however, AB-PAS staining revealed that the signet-ring-like cells had enriched cytoplasmic mucin, and other PDA-like cells also had more intracytoplasmic mucin than the original PDA cells. Here, MUC5AC is linked to Patent ductus arteriosus.