Fibroadenoma versus phyllodes tumor: a vexing problem revisited!

Area of Science:

• Oncology
• Pathology
• Cytopathology

Background:

• Fibroepithelial lesions of the breast encompass fibroadenoma (FA) and phyllodes tumor (PT).
• While FA is benign, PT exhibits a spectrum from benign to malignant, with metastatic potential.
• Accurate distinction between FA and PT is clinically significant.

Purpose of the Study:

• To identify specific cytologic features that reliably differentiate FA from PT.
• To enhance the preoperative diagnostic accuracy of fine needle aspiration (FNA) for fibroepithelial breast lesions.

Main Methods:

• Retrospective review of FNA specimens from patients with confirmed histopathology of FA or PT.
• Assessment of cytologic criteria including epithelial and stromal components, and background cellularity.
• Statistical analysis using univariate and generalized estimating equations (GEE) regression models.

Main Results:

• Analysis of 46 FA and 24 PT specimens.
• Significant cytologic predictors of PT included: large, folded epithelial sheets; frayed stromal contours; spindle stromal cell nuclei; background spindle cells; and background cellular atypia.
• The GEE model achieved 78.9% diagnostic accuracy in distinguishing PT from FA (p < 0.001).

Conclusions:

• Specific cytologic features observed on FNA can effectively distinguish PT from FA.
• The presence of large, folded epithelial sheets, irregular stromal fragments with spindle nuclei, and background atypia are key indicators of PT.
• These findings can improve the preoperative diagnosis of phyllodes tumors.