Résumé
Allergic Fungal Sinusitis [AFS] resembles allergic bronchopulmonary aspergillosis, resulting from hypersensitivity reaction to fungi mediated by IgE and IgG. A study of 20 patients from 1990 to 1998 suffering from AFS revealed that all presented with nasal, polypi. Most had atopy with raised serum IgE and high eosinophil count. Sandwiched between polypi are dark greenish brown concretions with high metal contents. A high concentration of glycoproteins and macromolecular protein was found in the contents. The lesion showed high attenuation on CT and void signal on MRI due to the presence of metals. Aspergillus was the most frequently found fugus followed by Bipolaris, Helmenthosporium and Curvularia. Polypi are surrounded by allergic mucin and Charcot-Leyden crystals interspersed with fungal hyphae. The eosinophilic host response to the fungi in the susceptible individuals leads to cascade of inflammatory reactions initiating IgE mediated hypersensitivity, specific T-cells HLA receptor expression and aberration of local mucosal defence mechanism resulting in AFS