Allergic fungal sinusitis - new aspects of clinical features, laboratory diagnosis and therapy

Abstract

Allergic fungal sinusitis (AFS) is a chronic non?invasive disease. Hypersensitive immune response is usually initiated by allergens of filamentous fungi Aspergillus, Penicillium, Cladosporium, Fusarium, Bipolaris, Curvularia and Alternaria. AFS is a clinical and immune analogue of the allergic bronchopulmonary aspergillosis (ABPA) as the sinus exudate resembles that of the bronchoalveolar lavage (BAL) in ABPA. Patients with AFS are usually immunocompetent, atopic and males. The most common symptoms are headache, fullness in the paranasal sinuses, and difficult breathing through the nose. Clinically, there is a chronic mucosal inflammation and histopathologic finding shows allergic mucin and eosinophils. Specific staining methods, Gomori?s Methenamine Silver (GMS) or periodic acid?Schiff (PAS), are used for microscopic visualisation of hyphae, which are, in addition to the isolated fungi, most reliable evidence of AFS. Computerized tomography (CT) of paranasal sinuses shows the areas of hyperdensity. In cases where AFS is complicated by the erosion of bone tissue, discontinuation of the sinus bone wall can be seen. Significant laboratory finding, which correlate highly with the AFS, are high immunoglobulin E (IgE) antibodies specific for fungi, detected by the skin prick test or in serum. Treatment is often surgical, and after removal of the allergic mucin, therapy involves oral and nasal corticosteroids, immunotherapy and locally applied antimycotics (with verified fungal etiology). During treatment, the total/specific IgE is monitored - concentration increases with the development of AFS, and decreases during the improvement process. Knowledge of the pathophysiological mechanisms of AFS is scarce, and represents the focus of further research in order to define an optimal diagnostic and therapeutic approach.