We report a case of a pancreatic mucin-producing cystic tumor with carcinoma in situ of the dilated main pancreatic duct detected by immunohistological staining. The patient, a 76-year-old man, was admitted for enlargement of pancreaticcysts and elevation of CEA and CA19-9, although small cysts of the tail of the pancreas were found 5 yearsearlier. Distal pancreatectomy was performed because of a strong suspicion of malignancy. Macroscopically, multiple cysts were located in the whole pancreas and communicated with the main pancreatic duct. By histological examination of the whole specimen cut into 1.5 mm sections, the only lesion of dilated main pancreatic duct was diagnosed as carcinoma in situ because of swelling of the nuclei, increase in chromatin, distinct nucleoli and disappearance of cell polarity. The lesion was strongly stained immunohistologically in the apical portion and cytoplasm of cells by CEA.
- carcinoma in situ
- immunohistological CEA staining
- pancreatic mucin-producing cystic tumor