[The proliferative activity in epithelial hyperplasia of the breast].

Epithelial hyperplasia of the breast has been recognized as an indicator of the risk for occurrence of invasive ductal carcinoma. In the future, however, its biological nature as well as precancerous potency remains unclear. Therefore, in order to elucidate a part of its biological nature, we attempted to evaluate proliferative activity in 62 lesions of epithelial hyperplasia of the breast, by means of immunohistochemistry of Ki-67 and silver stain of nuclear organizer region (NOR). Consequently, the labelling index (LI) of Ki-67 and the number of AgNOR became larger according to the increased grade of stratification, but cellular atypia without significant stratification also showed large LI of Ki-67 and number of AgNOR. Moreover, it was suggested from the discrepancy in the results of Ki-67 and AgNOR that AgNOR and Ki-67 reflected different phenomena.