Background and Objectives:
The correlation between various levels of perineural invasion by pancreatic carcinoma and the patient's prognosis has never been cleared. The authors carried out a histopathologic study of resected pancreatic carcinoma to elucidate the significance of a new histologic finding concerning perineural invasion, which we designated ''intrapancreatic, extratumoral perineural invasion (nex),'' and also to determine its predictive value for prognoses of patients after surgical removal of the tumor. Methods: We investigated 90 patients with pancreatic adenocarcinoma who had undergone pancreatic resection. The prognoses of all patients were explored, and correlations between survival and pathologic factors were statistically examined for neural invasion. Results: Nex was found in more than 50% of resected pancreases. A statistically significant association was found between the presence of nex and the grade of intrapancreatic neural invasion or the presence of extrapancreatic neural plexus invasion. Nex was also found to be associated with patient survival after removal of the tumor. Conclusions: Nex appears to be an element predicting pancreatic cancer infiltration to the extrapancreatic nerve plexus and also to be a factor influencing postoperative survival of patients with pancreatic carcinoma.