A teenage girl presented with new onset of bilateral upper extremity numbness and paresthesias. The rest of the clinical history and neurological examination was unremarkable. A magnetic resonance imaging (MRI) study of the brain and cervical spine obtained to evaluate for demyelinating disease demonstrated a normal brain and cervical cord, but an incidental T2 hyperintense lesion within the right pterygoid muscles was noted. On further consultation with the otolaryngology department, the patient stated that she had not experienced any sensation of a mass, and results from a focused otolaryngologic examination were also normal. A dedicated fifth cranial nerve MRI examination performed to better characterize the lesion revealed a well-defined, lobulated T2 hyperintense lesion within the right pterygoid muscles without mass effect, adjacent edema, or other invasive features (Figure, A). There was a small focus of signal void on the T2-weighted images, suspicious for tiny calcification. On gadolinium administration, there was sequential increased enhancement on the postcontrast T1-weighted axial images (Figure, B and C). Further imaging workup with single-proton emission computed tomography-CT (SPECT-CT) using technetium Tc 99m–labeled red blood cells (RBCs) demonstrated increased tracer pooling within the lesion (Figure, D).
Patel J, Brown RKJ, Bradford CR, Srinivasan A. Incidental Masticator Space Lesion in a Teenager. JAMA Otolaryngol Head Neck Surg. 2015;141(6):577-578. doi:10.1001/jamaoto.2015.0265