Immunostaining Patterns of CD10 in Fibroadenomas and Phyllodes Tumours of Breast

Background: Accurate differentiation between fibroadenomas and phyllodes tumours (PTs) is challenging due to overlapping morphological features. CD10, an immunohistochemistry (IHC) marker, has shown promise in distinguishing these breast lesions. This study aimed to evaluate CD10 expression patterns in fibroepithelial lesions (FELs) of the breast. Methodology: This cross-sectional study was conducted in the Histopathology Department, at Dow University of Health Sciences over 1 year (01st Jan 2023 to 15th Dec 2023). Through the purposive sampling technique, the female patients having FELs were diagnosed by Consultant Pathologists as fibroadenomas or PT and were included in the study by employing specific histological parameters on H & E slides. Immunohistochemistry with CD10 antibody was conducted on a total of 120 samples with an equal split of fibroadenomas, benign PT, borderline PT, and malignant PT (30 cases each), assessing stromal cell staining and categorizing expression as negative (<10% positivity), weak (10–30% positivity), or strong (>30% positivity). Data was statistically analyzed by using SPSS version 26 including reporting mean ± S.D for continuous data and utilizing the Chi-square test to assess associations, with significance set at p<0.05. Results: Negative CD10 expression was observed in fibroadenomas and benign PT, while borderline and malignant PT exhibited weak and strong positive CD10 expression. The analysis revealed a highly significant association (p-value < 0.001) between CD10 expression levels and the various forms of breast lesions. This strong statistical correlation indicates that CD10 could be an important biomarker for assessing the nature of breast lesions. A low p-value reinforces the reliability of the findings, suggesting that the observed differences in CD10 expression are unlikely to be due to random chance. Conclusion: The findings of the study suggest that CD10 expression could assist as a valuable marker for differentiating between FELs of the breast. Moreover, it may serve as an indicator of the aggressiveness and metastatic potential of PT.