OBJECTIVETo characterize clinicopathological features of allergic fungal sinusitis (AFS).

METHODSThirty-six cases of AFS were retrieved from the department archival files of Beijing Tongren Hospital from 2002 to 2006. AB-PAS, GMS and MUC5B stain were performed using paraffin-embedded tissues of the cases. Ten cases with available fresh diagnostic tissue were investigated by electron microscopy.

RESULTSPatients included 21 males and 15 females. The age of patients ranged from 11 to 53 years. Atopy was very common in these patients. On plain CT scans, the affected nasal sinuses were filled with soft tissue shadow with patchy hyperdensity. The bony sinus wall showed areas of pressure erosion. Skin antigen tests showed fungal positivity in 31 of 36 cases. Serum levels of the total IgE and/or the specific fungal IgE were elevated in 20 cases. The eosinophil quantity was elevated in 23 cases. Fungal culture was positive in 10 cases. Gross examination showed thick putty secretions within the lesions. Light microscopy showed typical "eosinophilic mucin". Fungal elements were seen with AB-PAS, GMS and MUC5B stains. Electron microscopy demonstrated degranulation by the eosinophils.

CONCLUSIONS"Eosinophilic mucin" is the typical histopathological feature of AFS. AB-PAS, GMS and MUC5B staining methods can used to detect fungal species in mucin. Accurate diagnosis of AFS requires correlations among clinical findings, radiologic examinations, laboratory tests and histopathologic features. However, the ultimate diagnosis requires a histopathologic confirmation.