Allergic fungal sinusitis: a clinicopathologic study of 16 cases.

Allergic fungal sinusitis (AFS) has been clinicopathologically defined as a noninvasive form of fungal infection. Etiologically, most reported cases have been attributed to pigmented dematiaceous fungi. The authors report 16 cases of AFS from our institution, along with a review of cases from the literature. The patients' age ranged from 8 to 71 years, with a mean age of 25 years. All patients were immunocompetent, although six had a strong history of atopy. Multiple sinuses were affected in all cases; nine patients had bilateral involvement, and seven patients manifested unilateral involvement. Histopathologically, all cases were characterized by the presence of "allergic mucin," with scattered fungal organisms without invasion of mucosa or bone. Fontana-Masson stain identified fungi in all but one case and assisted in distinguishing the pigmented dematiaceous organisms from other septated fungal forms. Accordingly, Fontana-Masson stain can be useful in confirming the diagnosis of AFS in the lack of tissue culture results. Fungal cultures performed on six cases grew Exserohilum (three cases), Bipolaris (one case), Drechslera (Bipolaris) (one case), and Curvularia (one case). All patients were treated with surgical debridement and sinus aeration. Follow-up of at least 6 months was obtained in six cases, of which four showed recurrent disease between 8 months and 4 years after the initial surgical procedure. A literature review showed that the most common etiologic agents were members of the dematiaceous family (81%), with the most common genus being Bipolaris (42%), followed by Curvularia (21.3%). It is believed that type I and III hypersensitivity reactions underlie the pathogenesis of this disease.