p53 protein accumulation in tumors of the ampulla of Vater

Background. Accurate preoperative diagnosis of tumors of the ampulla of Vater is difficult because ampullary biopsies have a high false‐negative rate. Recently, it has been suggested that p53 mutations in tumors of the ampulla of Vater are associated with the transformation of adenomas and low grade carcinomas to high grade carcinomas. The purpose of this study was to determine the extent of p53 protein accumulation in tumors of the ampulla of Vater, and to determine whether p53 accumulation can be detected in false‐negative biopsies. Methods. Using a monoclonal anti‐p53 antibody, sections of 4 normal ampullas, 5 adenomas, 17 carcinomas, and 9 initial biopsies of 9 of the tumors of the ampulla of Vater that had no morphologic evidence of carcinoma were immunostained. Results. None of the 4 normal ampullas (0%), 2 of 5 adenomas (40%), and 16 of 17 carcinomas (94%) were positive for p53. This p53 positivity was present through all stages of ampullary carcinoma. Of the nine initial biopsies negative for carcinoma, seven were positive for p53 and, of these, six (86%) were found to be carcinomas upon resection. Conclusions. 1) The molecular events leading to p53 accumulation in tumors of the ampulla of Vater occur early in the neoplastic process. 2) Tumors of the ampulla of Vater with biopsies negative for malignancy but positive for p53 are very likely to be carcinomas.