Metastatic breast carcinoma. A, Axial FLAIR images demonstrate a solitary mass with extensive surrounding edema in the left subinsular region. B, Axial and coronal enhanced Tl -weighted images show ring enhancement. Although the differential for a solitary mass lesion includes primary neoplasms and infectious etiologies, the peripheral location of this lesion, and the disproportionate amount of edema incited by the mass suggest metastatic disease. (Click to magnify figure)

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