De-escalating indications for excision when breast core needle biopsy returns fibroepithelial lesion—not further characterized

Purpose Surgical excision is often performed to exclude phyllodes tumor (PT) when Core Needle Biopsy (CNB) of the breast returns fibroepithelial lesion—not further characterized (FEL-NFC). If imaging or CNB pathology features can be identified that predict a very low probability of borderline/malignant PT, thousands of women could be spared the expense and morbidity of surgical excisions. Methods This retrospective cohort study includes 180 FEL-NFC from 164 patients who underwent surgical excisional biopsy. Results The upgrade rate from FEL-NFC to benign PT was 15%, and to borderline/malignant PT 7%. Imaging features predicting upgrade to borderline/malignant PT included greater size ( p = 0.0002) and heterogeneous echo pattern on sonography ( p = 0.117). Histologic features of CNB predicting upgrade to borderline/malignant PT included “pathologist favors PT” ( p = 0.012), mitoses ( p = 0.014), stromal overgrowth ( p = 0.006), increased cellularity ( p = 0.0001) and leaf-like architecture ( p = 0.077). A three-component score including size > 4.5 cm ( S ize), heterogeneous echo pattern on sonography (Heterogeneity), and stromal overgrowth on CNB (Overgrowth) maximized the product of sensitivity x specificity for the prediction of borderline/malignant PT. When the SHO score was 0 (72% of FEL-NFC) the probability of borderline/malignant PT on excision was only 1%. Conclusion The combination of size ≤ 4.5 cm, homogeneous echo pattern, and absence of stromal overgrowth is highly predictive of a benign excision potentially sparing most patients diagnosed with FEL-NFC the expense and morbidity of a surgical excision.