Benign
phyllodes tumors and
fibroadenomas are two types of fibroepithelial
tumors of breast that are usually difficult to differentiate. The purpose of this study is to evaluate the proliferative activity of these
tumors and to find out if it helps in differential diagnosis. Thirty-one benign
phyllodes tumors and twelve cellular
fibroadenomas were retrieved from the archives of Pathology Department of Akdeniz University, School of Medicine. Proliferating activity of epithelial and stromal cells were evaluated by using labeling index (LI) of
proliferating cell nuclear antigen (
PCNA) and
Ki-67 antigen by immunohistochemistry. The results were compared with other clinicopathologic findings. There was not any significant difference between the proliferating activity of
phyllodes tumor and cellular
fibroadenomas. Mean LI of
PCNA was 28.01 (+/-22.85) in stromal cells and 56.57 (+/-30.98) in epithelial cells of
phyllodes tumor where it was 28.92 (+/-24.02) and 62.53 (+/-32.56) in
fibroadenomas. Ki-67 indices were 0.05 (+/-0.19) in stromal cells, 2.65 (+/-12.53) in epithelial cells of
phyllodes tumors and 0.0 (+/-0) in stromal cells, 0.43 (+/-0.63) in epithelial cells of
fibroadenomas. There was no correlation between the diameter of
tumors and proliferating activity in both groups. Proliferating activity, determined by immunohistochemistry with
PCNA and Ki-67
antibodies did not reveal significant difference between
phyllodes tumor and
fibroadenoma.