Fibroepithelial Lesion Spectrum: A Case Report Documenting a Possible Transformation to a Malignant Phyllodes Tumor

Abstract

We discuss the radiological-pathological aspects of a rare case of transformation of a presumed fibroadenoma (FA) to a malignant phyllodes tumor (PT) and review the literature. Phyllodes tumors often show heterogeneous histologic features with some areas indistinguishable on core needle biopsy. A core biopsy is often a small representation of a larger lesion. As such, a complete excisional biopsy is often needed for a definitive pathologic diagnosis. Careful clinical and imaging correlation and follow-up are necessary, even in a benign fibroepithelial lesion (FEL).

Keywords: breast; fibroadenoma; fibroepithelial lesion; phyllodes; transformation.

Figure 1. Breast ultrasound demonstrates a well-defined ovoid hypoechoic 1 cm nodule.

Figure 2. Ultrasound 32 months later demonstrates a hypoechoic 2.8 cm mass that has increased in size, with heterogeneity and lobulations.

Figure 3. Malignant phyllodes tumor showing (A1) leaf-like growth and variable cellularity including high stromal cellularity, (A2) high stromal cellularity and marked nuclear atypia, (A3) mitotic figures including atypical mitotic figures.