Comparative Histological Features of Phyllodes Tumor and Fibroadenoma in Breast Core Needle Biopsies.

BackgroundPhyllodes tumors (PT) are fibroepithelial breast lesions with variable clinical behavior and histological features that frequently overlap with those of fibroadenomas. Accurate differentiation is critical, as PT may exhibit aggressive behavior. However, their distinction is particularly challenging in core needle biopsy, especially for benign and borderline PT, due to the limited amount of tissue provided by this technique. This meta-analysis investigates histological features that improve the distinction between fibroadenomas and PT in core needle biopsies.MethodsWe searched databases for studies comparing the core needle biopsy histologic features of lesions diagnosed as fibroadenoma or PT in the follow-up histopathological evaluation of the surgical specimen.ResultsWe included 14 studies, comprising 1413 patients. The PT group exhibited significantly higher rates of infiltrative margins (OR 6.06; 95% CI 2.13-17.22;  < .01), peri-epithelial stromal accentuation (OR 3.66; 95% CI 1.62-8.24;  < .01), stromal fragmentation (OR 6.93; 95% CI 2.66-18.04;  < .01), stromal overgrowth (OR 5.06; 95% CI 2.46-10.38;  < .01), cellular atypia (OR 9.04; 95% CI 5.15-15.89;  < .01), mitotic activity (OR 11.88; 95% CI 5.26-28.87;  < .01), and stromal hypercellularity (OR 9.67; 95% CI 5.58-16.78;  < .01). However, no statistically significant differences were found between the groups regarding the presence of adipose tissue within the lesion (OR 2.69; 95% CI 0.78-9.23;  = .12) or the presence of intracanalicular pattern (OR 1.02; 95% CI 0.55-1.92;  = .94). PTs were more frequent among older patients (MD 2.88; 95% CI 0.85-4.91;  < .01) and were larger (MD 1.07; 95% CI 0.79-1.35;  < .01).