Rhabdomyosarcoma Metastasis to the Breast: Appearance on Diffusion-Weighted Imaging and Apparent Diffusion Coefficient Sequences

Rhabdomyosarcoma is a common primary childhood malignancy that rarely metastasizes to the breast. We report a patient with a primary sinonasal rhabdomyosarcoma metastasizing to the breast, with no distant spread. We describe the imaging appearance of rhabdomyosarcoma on magnetic resonance imaging (MRI), particularly on diffusion-weighted imaging (DWI) and apparent diffusion coefficient ( ADC) sequences. Rhabdomyosarcoma metastasis has a variable appearance on ultrasound and MRI, and may mimic common benign tumors. However, it appears hyperintense on DWI and produces a low value on the ADC, which may be more accurate for determining its malignant nature.