Ill-defined margins as a sign of malignancy. Ill-defined margins as a sign of malignancy. A, Warthin tumor with a well-defined border on axial T2-weighted imaging (arrows) in a 66-year-old man. B, Postcontrast T1-weighted imaging of Warthin tumor (arrows). C, Ill-defined margin (arrows) of a mucoepidermoid carcinoma in a 61-year-old male patient with SI similar to that in the Warthin tumor (A). Note the low SI on the T2-weighted image, which is also a malignant predictor. D, Postcontrast T1-weighted image of the ill-defined mucoepidermoid carcinoma (arrows). A. Christe et al. AJNR Am J Neuroradiol 2011;32:1202-1207 ©2011 by American Society of Neuroradiology