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Allergic fungal sinusitis: a clinicopathologic study of 16 cases
C Torres1, J Y Ro, A K el-Naggar
1Department of Pathology, University of Texas, M.D. Anderson Cancer Center, Houston 77030, USA.
Abstract:
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.
Insights
Allergic fungal sinusitis (AFS) is a noninvasive fungal infection often caused by dematiaceous fungi. Diagnosis can be aided by Fontana-Masson stain, and treatment involves surgical debridement, though recurrence is possible.
Area of Science:
- Otolaryngology
- Mycology
- Immunology
Background:
- Allergic fungal sinusitis (AFS) is a distinct clinicopathological entity characterized as a noninvasive fungal infection.
- Pigmented dematiaceous fungi are frequently implicated as the etiological agents in AFS.
- Understanding the pathogenesis and diagnostic markers is crucial for effective management.
Purpose of the Study:
- To report 16 cases of AFS from the authors' institution.
- To review existing literature on AFS etiology and clinical presentation.
- To evaluate the utility of Fontana-Masson stain in diagnosing AFS.
Main Methods:
- Retrospective analysis of 16 AFS cases.
- Histopathological examination of sinus tissues, including special stains (Fontana-Masson).
- Literature review of AFS cases and etiologic agents.
Main Results:
- 16 immunocompetent patients (age 8-71) with AFS were identified; six had atopy.
- All cases presented with "allergic mucin" and scattered fungi without tissue invasion.
- Fontana-Masson stain identified fungi in 15/16 cases, aiding in the identification of dematiaceous fungi.
Conclusions:
- Fontana-Masson stain is a valuable diagnostic tool for AFS, particularly when fungal cultures are negative or unavailable.
- Dematiaceous fungi, especially Bipolaris and Curvularia, are the most common causes of AFS.
- While surgical debridement is the primary treatment, AFS has a significant recurrence rate, suggesting underlying hypersensitivity mechanisms.