Nerve Plexus Invasion in Pancreatic Cancer Spread Patterns on Histopathologic and Embryological Analyses

Objectives: Although extrapancreatic nerve plexus (PLX) invasion is an important prognostic factor in pancreatic carcinoma, the spreading patterns of carcinoma via PLX have not been carefully explored because of the complex anatomical structures around the pancreas. Methods: Fifty-eight patients underwent pancreaticoduodenectomy for carcinoma of the head of the pancreas. The patterns of PLX invasion were evaluated by careful pathological examination. The relationship between tumor location considering the embryological structure of the pancreas and the site of PLX invasion was investigated with an immunohistochemical study using pancreatic polypeptide. Results: Forty-six patients (79%) had PLX invasion. The typical patterns of PLX invasion were detected by pathological examination. Patients with carcinoma in ventral pancreas frequently had pancreatic head plexus 1, pancreatic head plexus 2, and superior mesenteric arterial plexus invasion. Patients with carcinoma in dorsal pancreas had invasion into common hepatic artery plexus and plexus within the hepatoduodenal ligament. A significant correlation between tumor location and the site of PLX invasion was observed. Conclusions: Extrapancreatic nerve plexus invasion by carcinoma of the head of the pancreas could be divided into 2 patterns based on an embryological structure of the pancreas and the location of the tumor. These results about PLX invasion may provide important information to determine surgical strategy for carcinoma of the head of the pancreas.