Allergic fungal sinusitis. A naso-sinusal specific hyperreactivity for an infectious disease?

Allergic fungal sinusitis (AFS) is a rare disease of naso-sinusal complex affecting mainly young, immunocompetent adults who complain of chronic rhinitis and/or recurrent nasal polyposis despite medical and/or surgical treatment. Aim of the study is to analyse, from an allergological and otorhinolaryngological point of view, patients affected by the so-called "allergic fungal sinusitis" in order to better define the relationship between fungi present in naso-sinusal secretions and the host's immunoreactivity. From February 2001 to January 2002, 24 selected patients (13 male 11 female) age range 25-65 years (mean 45), with chronic rhinosinusitis, with a positive fungal examination of nasal secretion, underwent allergological evaluation. All patients were positive for diagnostic criteria of allergic fungal sinusitis and, in all patients, nasal lavage was performed for microscopic examination by fluorescence. Samples were then cultured on Sabouraud growth media for identification of the fungus. Skin prick tests (SPT) were then performed with the 15 main inhalant allergens and twelve fungal allergens (Bracco). The total IgE serum level (PRIST), the specific fungal IgE and the eosinophilic cationic protein were then investigated by means of an immuno-fluorine enzymatic method. Finally, a nasal provocation test was carried out with diluted solutions (1/100, 1/10) and with a pure solution of fungal allergens, selected according to microbiological examination of nasal secretion of each subject. Prick tests were positive for seasonal and perennial allergens in 5 patients (21%), while prick tests with fungi were positive in only 4 patients (16.6%). Total IgE levels were higher than in normals (200 KU/l) in 6 patients (25%) (mean 364.74 KU/l). In another 18 patients, total IgE were normal. Specific IgE levels for the tested fungi and eosinophilic cationic protein levels were within normal range in all patients. Nasal provocation test was negative in all patients. Presence of fungi in nasal secretions of patients with AFS does not appear to be correlated with an allergic status to the isolated fungus. A role for IgE in either the aetiology or the pathophysiology of allergic fungal sinusitis in unlikely, and probably the diagnostic criteria for allergic fungal sinusitis should not include type I hypersensitivity, since no confirmed evidence exists that IgE-mediated type I hypersensitivity is involved in the pathophysiology of allergic fungal sinusitis.