Epithelial hyperplasia of the breast. Comparison of incidence between cases of breast carcinoma and control autopsy specimens with immunohistochemical observation of blood group antigens.

Epithelial hyperplasia in the duct, ductule or lobule of the breast is a very common lesion and has been considered to carry a risk of subsequent invasive carcinoma. However, it is not known whether epithelial hyperplasia can transform into carcinoma or whether malignant change occurs de novo. We analyzed the incidence of epithelial hyperplasia of the breast by making a comparison between cases of breast carcinoma and control autopsy specimens, and studied differences in the membrane antigens of the constituent cells using immunohistochemical staining of blood group antigens. It was found that the frequency of epithelial hyperplasia was higher in the cases of breast carcinoma. The lesions showed loss of A, B and H antigens at high frequency, and the proportion of lesions showing loss of these antigens became higher as the atypia of the lesion increased. On the other hand, expression of Lea antigen was observed more frequently in atypical epithelial hyperplasia or in situ carcinoma than in ordinary epithelial hyperplasia. These findings suggest possible transformation from epithelial hyperplasia to carcinoma, and indicate that atypical epithelial hyperplasia may be precancerous in nature.