A 41-YEAR-OLD man who presented with a several-year history of trismus was found to have a 1.5-cm lesion of the right glenoid fossa during radiologic evaluation for dysequilibrium. He denied otalgia, malocclusion, and difficulty with mastication. One year later, follow-up magnetic resonance imaging (MRI) and computed tomographic (CT) scans showed an increase in the size of the mass. The CT scans showed an expansile process of the temporomandibular joint (TMJ) containing foci of calcifications (Figure 1). There was also thinning and erosion of the bony floor of the middle fossa. T1-weighted MRI scans showed a well-circumscribed lesion in the glenoid fossa, with a central hypointense region (Figure 2) and a surrounding isointense region that enhanced with gadolinium. Physical examination revealed that the patient had mild trismus with no deviation of the jaw from midline on mouth opening. There were no palpable masses in the preauricular, parotid, or cervical regions. The findings of the otoscopic examination were unremarkable. At surgery, a soft tissue mass of rubbery consistency was seen in the glenoid fossa, eroding through the middle fossa floor. The histopathologic findings are shown in Figure 3 and Figure 4.
Jiang W, Mishra S, Francis HW. Quiz Case 4. Arch Otolaryngol Head Neck Surg. 2000;126(7):903-908. doi: