A 72-year-old man presented with a 1-year history of right-sided nasal obstruction, right exotropia, and diplopia. Endoscopic examination revealed a reddish solid mass occupying the right middle meatus, with prominent bulging of the lateral nasal wall. The contralateral nasal cavity and nasopharynx were unremarkable.
A computed tomographic scan of the paranasal sinuses (Figure 1) demonstrated a soft-tissue mass emerging from the right maxillary sinus, with extension into the right nasal cavity, and intraorbital extraconal extension. Precontrast magnetic resonance imaging (MRI) of the brain and sinuses revealed a well-circumscribed mass in the right maxillary sinus extending to the right ethmoidal sinus and orbital cavity. The lesion was hypointense on T1-weighted images (Figure 2) and heterogeneously hyperintense on T2-weighted images (Figure 3) and showed heterogeneous enhancement after the administration of gadolinium (Figure 4). The mass was surgically removed via a transnasal endoscopic approach and sent for histopathologic analysis.
What is your diagnosis?