Fibroepithelial breast lesions diagnosed by core needle biopsy demonstrate a moderate rate of upstaging to phyllodes tumors

- Breast fibroepithelial lesions (FEL) are atypical lesions diagnosed on core needle biopsy.
- This study determines the rate of FEL upstaged to phyllodes tumor (PT) on excisional biopsy.
- The excision of 48 FEL yield a diagnosis of Phyllodes tumor in 37.5% of cases: 29.2% benign, 8.3% borderline, 0% malignant.
- On preoperative ultrasound, PTs demonstrate heterogeneous echotexture and a higher BIRADs score (≥4b).
- We recommend a low threshold to proceed with surgical management of FEL given the moderate upstage risk to PT.

BackgroundFibroepithelial lesions of the breast (FEL) are atypical lesions diagnosed on core-needle biopsy. The purpose of this study was to determine the rate at which FELs are upstaged to phyllodes tumor on excision, and to examine the clinical and radiological factors that may be predictive of upstaging.MethodsA retrospective review from the medical records of patients diagnosed with FEL on CNB at a single institution between 2010 and 2015 was performed. Patients diagnosed with benign or borderline phyllodes tumors were compared to those diagnosed with fibroadenoma.ResultsOf 74 patients diagnosed with FEL, 48 underwent excision (64.9%). Of the 48 lesions excised, pathology revealed 30 fibroadenomas (62.5%), 14 benign phyllodes tumors (29.2%), and 4 borderline phyllodes tumor (8.3%). No malignant phyllodes tumors were identified. On preoperative ultrasound, heterogeneous echotexture (p = 0.03) and lack of internal vascularity (p = 0.03) were significantly associated with upstaging to phyllodes tumor.ConclusionsSurgical excision of FELs yield a pathological diagnosis of benign and borderline phyllodes tumor in 37.5% of cases. A high BIRADs score (≥4b), heterogeneous echotexture and lack of internal vascularity on ultrasound may help predict upstaging to phyllodes tumor.