Immunohistochemical expression of Ki-67, p53, and CD10 in phyllodes tumor and their correlation with its histological grade

CONTEXT: Phyllodes tumors (PTs) are the fibroepithelial neoplasms of the breast. Histologically, PTs are divided into three subgroups according to their clinicopathological behavior: benign, borderline, and malignant. It is at times difficult to ascertain the grade of PT on morphological criteria alone, especially borderline PT may be at times difficult to distinguish from its benign or malignant counterparts. AIMS: This study was undertaken to evaluate an immunohistochemical panel of Ki-67, p53, and CD10 in PT and to determine their expression in PT in correlation with its grade. SETTINGS AND DESIGN: This was a retrospective study. SUBJECTS AND METHODS: The study included six malignant, six borderline, and twelve benign PT. Expressions of Ki-67, p53, and CD10 were evaluated on all the 12 cases and compared in these three categories. STATISTICAL ANALYSIS USED: Chi-square test was applied, and P < 0.05 was taken as statistically significant. RESULTS: Stromal expression of Ki-67 and p53 between the benign and borderline/malignant group showed a statistically significant difference. Neither CD10 expression nor epithelial expressions of Ki-67 and p53 were found significant. Periepithelial accentuation of Ki-67 and p53 immunostaining was noted in all positive cases. CONCLUSIONS: Ki-67 labeling index and p53 immunostaining can be a useful adjunct to determine the grade in difficult cases. However, no single immunomarker can reliably distinguish between benign and borderline phyllodes in all cases.