Indications for the surgical excision of fibroadenomas: systematic review

Background: The differentiation between fibroadenomas and phyllodes tumors (PTs) is often difficult to establish based on core needle biopsy (CNB) alone due to similarities on pathologic evaluation and sampling error. Lesions for which a determination cannot be made are called fibroepithelial lesions (FELs). Since the surgical management of fibroadenomas and PT differ, we sought to determine the prevalence of PT on open surgical biopsy that were initially diagnosed to be fibroadenoma or FEL on CNB. Methods: We combined an institutional chart review over a five-year period with a systematic review of the literature (2010–2020) to determine how many breast masses were upgraded to PT or other malignancy following surgical excision. A search of Cochrane, Scopus and Medline databases was performed using the following search terms: “fibroadenoma”, “fibro adenoma”, “fibroepithelial lesion”, “fibro-epithelial lesion”, “core needle biopsy”, and “CNB with ultrasound”. Individual studies were assessed for bias using the ROBIS (Risk of Bias in Systematic Reviews) tool. Results: A total of 357 articles were retrieved from the databases; 45 additional articles were identified from references of relevant papers. A total of 273 unique articles were identified and reviewed for relevance; 14 articles met all criteria for inclusion in the review. Of the 1,908 CNB diagnosed as fibroadenoma or FEL that were surgically excised, the final pathology after open biopsy was fibroadenoma (n=1,409, 73.8%), PT (n=492, 25.8%), and other malignancy (n=7, 0.37%). If the CNB showed fibroadenoma, the negative predictive value (NPV) is 98%, whereas FEL on CNB has a NPV of 65%. Of all the PT resected, 86% were benign PT. Conclusions: Fibroadenomas diagnosed on CNB rarely harbor malignancy and most of these lesions may be clinically observed. FELs diagnosed on CNB may also undergo clinical surveillance if less than 2 cm in size due to the low risk of PT. A limitation of our study is that all the data are derived from retrospective data.