Magnetic resonance imaging revealed a spherical lesion in the masticatory space. The lesion, which measured 25 × 28 × 26 mm, was deep to the attachment of the masseteric muscle, onto the zygomatic arch, and partially surrounded by the upper portion of the muscle itself. It was characterized by regular boundaries; its uppermost and deepest portion reached the internal maxillary artery, which was slightly displaced (Figure 1). On turbo spin-echo T2-weighted sequences, it appeared moderately hyperintense with respect to muscles and had a very hyperintense central portion, suggesting cystic changes (Figure 2). After contrast agent administration, spin-echo T1-weighted and 3-dimensional gradient-echo sequences showed peripheral enhancement and a nonenhancing central (cystic) portion (Figure 3and Figure 4). The lesion's site, regular margins, relationship to adjacent structures, and enhancement pattern suggested a neurogenic neoplasm. Based on the noninfiltrative pattern along with the basal and postenhancement characteristics, the lesion could reasonably be considered a benign mesenchymal tumor.
Radiology Quiz Case 2: Diagnosis. Arch Otolaryngol Head Neck Surg. 2011;137(6):632-633. doi:10.1001/archoto.2011.82-b