The metastasis of extramammary malignancies into the breast is very unusual. Lymphoma, malignant melanoma, and rhabdomyosarcoma are the most common tumors that metastasize into breast tissue. The histological spectrum of breast masses in children and adolescents is different from that of adults. Imaging findings are useful for performing a diagnosis, but in a patient with a known malignancy, any enlarging breast mass, even one with a benign radiological appearance, should be investigated with a biopsy. In this article, we present the imaging findings of a 12-year-old female patient with breast metastasis of Ewing's sarcoma.