Immunohistochemical analysis of Ki-67, p53, p21, and p27 in benign and malignant apocrine lesions of the breast: Its correlation to histologic findings in 43 cases

We examined Ki-67, p53, p21, and p27 immunolocalization in 43 cases of apoc rine lesions of the breast and correlated these findings with histologic pa rameters to understand their biologic significance. Twenty cases were benig n, 1 case was borderline, and 22 cases were diagnosed as malignant, includi ng 9 intraductal and 13 invasive apocrine carcinomas. Both the ratio of Ki- 67-positive cases (17 of 21 [88.9%] versus 1 of 19 [5,3%]; P < .001) and th e Ki-67 labeling index of positive cases examined (15.0% versus 2.7%; P <.0 05) were significantly higher in malignant than in benign apocrine lesions. None of the benign or borderline cases was immunohistochemically positive for p53, but 15 of 22 malignant cases (68.2%) demonstrated p53 (P < .001), In addition, the ratio of p53-positive cases was significantly higher in hi gh nuclear grade cases (11 of 13 [84,6%]) than in intermediate nuclear grad e cases (4 of 9 [44.4%]; P < ,05), P53 immunoreactivity was also positively correlated with the nuclear grade of carcinoma cases examined in this stud y. Neither p21 nor p27 demonstrated any correlation with histologic paramet ers or findings of the apocrine lesions. Results of these studies suggest t hat Ki-67 and p53 may be good markers for differentiation between benign an d malignant breast apocrine lesions.