Imaging findings in phyllodes tumors of the breast

Purpose: To study the radiological appearance and pathological features of breast phyllodes tumors (PTs), and to enhance the recognition of the tumor.

Materials and methods: Clinical and imaging findings were retrospectively reviewed in 24 women with PTs confirmed by surgical pathology. All of the 24 patients had preoperative MRI and sonography, and 10 had preoperative mammography.

Results: The histologic findings were benign, borderline and malignant PTs in 16.7% (4/24), 45.8% (11/24) and 37.5% (9/24) of cases, respectively. The tumor size (p=0.001), irregular shape on sonographic imaging (p=0.039), internal non-enhanced septations (p=0.009), silt-like changes in enhanced images (p=0.006) and signal changes from T2-weighted to enhanced images on MRI (p=0.001) correlated significantly with the histologic grade; the BI-RADS category of the MRI could reflect the PT's histologic grade with a correlation coefficient of 0.440 (p=0.031). If the category BI-RADS ≥4a was considered to be a suspicious malignant lesion, the diagnostic accuracy of mammography, US and MRI would be 70% (7/10), 62.5% (15/24) and 95.8% (23/24), respectively.

Conclusion: The tumor size and several US and MRI findings can be used to help preoperatively determine the histologic grade of breast PTs. When a patient presents with a progressively enlarging, painless breast mass, MRI should be recommended first.