Diagnostic Role of Collagen Type III Alpha in Fibroepithelial Lesions of the Breast: An Immunohistochemical Study

Abstract

Abstract Background The fibroepithelial lesions (FELs) are heterogeneous biphasic tumors composed of epithelial and stromal components, they include fibroadenoma (FA) and phyllodes tumor (PT). The most FAs are benign, while the PTs have unpredictable biologic behavior, where they can recur if incompletely excised, and can even metastasize. According to the WHO Classification of Tumors of The Breast, PT is classified by the histological features into benign, borderline, and malignant. There is difference in management of the FELs, where a FA is treated conservatively or by simple enucleation. While PT must be excised with wide surgical margin to avoid the recurrence of this tumor, where it can recur as high grade. For this reason the preoperative distinction between FA and PT is critical for management. On another hand, still this differentiation is difficult and challenging in some cases especially on limited sample of core needle biopsy (CNB) and also on excision due to the heterogeneity of PT and overlapping features between the FELs. Recently, the use of immunohistochemical markers may have helpful role in differentiation between FA and PT, and grading of the last one. Collagen III α (Col A ) has been emerged as a potential new diagnostic maker useful in differentiation between fibroepithelial lesions. Methodology In this retrospective study we evaluated the histopathological features of Cases of FELs including FA and PT with its subgrades. We also evaluated an immunohistochemical diagnostic potential of collagen III α (Col A) in differentiating FA from PT, and categorizing the last one. Furthermore, correlations between Col A expression and clinicopathological parameters were performed. Results The staining expression of Col A was increased significantly in PTs when compared with FAs (P<) . Col A expression increased with increased grade of PT but without significant difference between benign PT and borderline PT, and between borderline PT and malignant PT. By pairwise comparison, there was a significant difference between CFA and benign PT according to Col A expression (P<) , and also between the typical FA and FA with PT like features (P<) . There was a trend of increased expression but did not reach the significance between FA with PT like features and benign PT (P=) . Distinct periductal cuffing pattern of Col A staining was present in all PTs and absent in most FAs (P<) , and only cases of FA with PT features exhibited this pattern. Conclusion Col A is a diagnostic marker can differentiate between FA and PT, especially between CFA and benign PT, and the Col A expression increased with increased grade of PT but without significant difference. FA with PT like features might be a distinct category that should be distinguished from typical FΑ as it may an initial event of tumor progression to PT.