Proliferating activity in the epithelial and stromal component of fibroadenomas and phyllodes tumours of the breast.

The aim of the study was an evaluation of PCNA and Ki-67 expression in the epithelial and stromal component of fibroepithelial tumours (FT) of the breast in correlation with morphological parameters. A series of 11 fibroadenomas (FA), including 8 cases of the cellular type (FAC), 19 benign phyllodes tumours (PTLGM), 8 bordeline (PTBM) and 6 malignant phyllodes tumours were assessed, using immunohistochemistry. The expressions of Ki-67 and PCNA in the epithelial component were significantly higher in PTLGM, when compared with FA and PTBM. A significant increase of Ki-67 and PCNA stromal expressions was associated with the progression from PTLGM to PTHGM. Our results show that Ki-67 and PCNA may be useful in the evaluation of stromal proliferation in phyllodes tumours (PT), which play an integral part in the progression from PTLGM through PTBM to PTHGM.