Usefulness of endoscopic biopsy using immunostaining of p53 and Ki-67 in tumors of the ampulla of Vater.

We investigated the diagnostic and prognostic value of p53 expression and proliferative activity, as indicated by the Ki-67, in endoscopic biopsy specimens. Specimens were immunologically stained with p53 and MIB-1 (Ki-67), and the MIB-1/Ki-67 labeling index (LI) was calculated. Classification of adenomas was based on findings of H&E-stained preparations into those with low- or high-grade atypia.