Critical appraisal of stromal CD10 staining in fibroepithelial lesions of breast with a special emphasis on expression patterns and correlation with WHO grading.

BACKGROUND: Fibroepithelial lesions of the breast are classified into fibroadenoma and phyllodes tumor (PT). Although WHO has established a well-defined grading system for PT, dilemma of discriminating borderline from malignant PT still exists. Stromal CD10 is a known poor prognostic factor in invasive breast cancer, its expression in fibroepithelial lesions of the breast is not well-documented. Till date, only one study has correlated the CD10 staining score with tumor grade in PT.

OBJECTIVE: To evaluate whether the differences in expression patterns of CD10 and staining intensity correlate with the degree of malignancy in fibroepithelial tumors of the breast.

MATERIALS AND METHODS: This is a retrospective study in which stromal CD10 expression was studied in 75 cases of fibroepithelial lesions of the breast using immunohistochemistry. Statistical analysis was performed using Chi-square test.

RESULTS: There was a statistically significant trend of increasing stromal expression of CD10 with increasing degree of malignancy (P = 0.001).

CONCLUSIONS: CD10 staining pattern and its scoring can assist the pathologist to accurately grade the PT of the breast for adequate treatment and can also be used as a target for the development of novel therapies.