Detection of extrapancreatic nerve plexus invasion of pancreatic adenocarcinoma - Cytokeratin 19 staining and K-ras mutation

Background. Neural invasion is known to be one of the aggressive characteri stics of pancreatic adenocarcinoma. However, there have been no systematic studies on intraoperative examination of neural invasion of pancreatic carc inomas after wide dissection of the retroperitoneum, paticularly at the sur gical margin. Methods, We performed intraoperative immunostaining on the frozen sections of several excised plexus specimens, using peroxidase-labeled anti-cytokera tin 19 antibody in 17 cases of resectable pancreatic car cinema. Postoperat ively, we also tried to detect occult micrometastasis by direct sequencing of the K-ms gene in the same samples. Results, Intraoperative staining for cytokeratin 19 was positive in 4 of 17 (23.5%) cases. Patients with margin-positive neural invasion had significa ntly worse prognosis than patients who were margin negative (P < 0.05). One patient had micrometastasis in the nerve plexus, revealed by K-ras mutatio n, whereas neither cytokeratin 19 staining nor postoperative pathological i nvestigation detected involvement of the analyzed portion. In the four pati ents margin-positive for cytokeratin 19 staining, the diagnosis of neural i nvasion by cytokeratin 19 staining was in agreement with the K-ras gene ana lysis. Conclusion, Intraoperative staining for cytokeratin 19 is useful for detect ing pancreatic cancer involvement of the neural plexus margin. The results can be also utilized as a prognostic indicator during the follow-up period.