Fungal rhinosinusitis: diagnosis and therapy

Fungal rhinosinusitis presents in five clinicopathologic forms, each with distinct diagnostic criteria, treatment, and prognosis. The invasive forms are acute fulminant, chronic, and granulomatous ("indolent") invasive fungal sinusitis. The noninvasive forms are fungal ball ("sinus mycetoma") and allergic fungal sinusitis (AFS). AFS is the most common form of fungal rhinosinusitis. Patients with AFS are atopic to aeroallergens including the involved fungal organism, immunocompetent, have nasal polyps and chronic allergic rhinosinusitis, often produce nasal casts, and may occasionally present with proptosis from orbital extension of disease. Sinus CT shows sinus mucosal hypertrophy and often hyperattenuation of sinus contents. Diagnosis is made from surgical histopathology with or without an associated positive surgical sinus fungal culture. The histopathology shows extramucosal allergic mucin that stains positive for scattered fungal hyphae and eosinophilic-lymphocytic sinus mucosal inflammation. Bipolaris spicifera is the most common fungus cultured. The immunopathology of AFS has been shown to be analogous to allergic bronchopulmonary aspergillosis. Treatment requires surgery and aggressive postoperative medical management with close follow-up. Medical treatment includes allergy medications, allergen immunotherapy, and in many cases the addition of oral corticosteroids. Although medical management clearly improves patient outcomes, more studies are needed because AFS recurrence rates remain high.