Incidence, sites of origin, and immunohistochemical and histochemical characteristics of atypical epithelium and minute carcinoma of the papilla of Vater.

To elucidate the relationship between atypical epithelial growth and cancer of the papilla of Vater, histologic, histochemical, and immunohistochemical observations were made of the autopsy cases of mainly elderly people. The atypical grades of the epithelium were histologically classified into five groups: normal epithelium, Group 1; mild atypism, nonmalignant, Group 2; moderate atypism, borderline, Group 3; severe atypism, possibly malignant, Group 4; and apparent carcinoma, Group 5. The incidences of each group in 576 autopsy cases were 65.8%, 30.0%, 3.1%, 0.9%, and 0.2, respectively. The atypical epithelia were observed with the highest incidence in the common pancreaticobiliary channel. The immunohistochemical stainings for cancer-associated antigens (carcinoembryonic antigen [CEA] and carbohydrate antigen 19-9 [CA 19-9]) and histochemical stainings for mucin (periodic acid-Schiff [PAS] and alcian blue [AB], pH 2.5 and pH 1.0) revealed that most of the Group 1 and 2 epithelia were negative for CEA and positive for AB, pH 2.5. Group 3 and 4 epithelia were negative for both CEA and AB, and Group 5 epithelia were positive for CEA but negative for AB (chi-square test, P less than 0.01). A combination of CEA and AB pH 2.5 stainings may be helpful in the histologic diagnosis of normal epithelium to mild atypism, moderate to severe atypism, and carcinoma. The study on the relationships between atypical epithelia showed that some carcinomas of the papilla of Vater may arise from atypical epithelia.