C. Invasive fungal sinusitis (mucormycosis) with perineural spread
Overall, imaging features are highly suggestive of invasive fungal sinusitis with distinctive perineural spread of infection along the facial nerve and occult spread to the mandibular nerve via their intraparotid intercommunication. The patient started taking antifungal therapy (liposomal amphotericin B), and a biopsy was performed from the cheek lesion that yielded granulomatous inflammation. The strong clinicoradiological suspicion of fungal disease prompted a functional endoscopic sinus surgery exploration, which revealed cheesy, purulent discharge in both maxillary sinuses. The posterior wall of maxillary sinus, which was destroyed and sequestrum-like, was sampled. Histopathological examination with a fluorescent stain (Calcofluor White Stain) and Gomori methenamine silver stain (as shown in Figure 2) revealed aseptate fungal hyphae, highly suggestive of mucormycosis. Automated culture reports showed good sensitivity to voriconazole, to which the patient showed good clinical response. Although perineural spread is classically encountered with head and neck malignant tumors, the diffuse maxillary sinusitis bilaterally without any mass in the presence of a history of cancer chemotherapy strongly suggests an infectious cause.