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Allergic fungal sinusitis. Report of three cases associated with dematiaceous fungi
G C Friedman1, R W Hartwick, J Y Ro
1Department of Pathology, University of Texas M.D. Anderson Cancer Center, Houston.
Abstract:
Most reported cases of allergic sinusitis have been attributed to Aspergillus, based on the morphologic features of the organisms in tissue sections. However, in most cases, cultures have not been done. This is a report of three cases of non-Aspergillus allergic fungal sinusitis. The patients' ages were 11, 16, and 43; two were male and one was female. Histopathologic study disclosed fungal organisms resembling Aspergillus. However, cultures of these patients' nasal secretions grew Drechslera, Exserohilum, and Bipolaris fungal organisms. The non-Aspergillus nature of these infections was further supported by positive Fontana-Masson melanin staining. The authors conclude that allergic fungal sinusitis most likely results from non- Aspergillus organisms. For definitive fungal identification, tissue culture is mandatory. When tissue is not cultured or no organisms grow, a Fontana-Masson stain can be a useful adjunct in fungal identification.
Insights
Allergic fungal sinusitis is often misattributed to Aspergillus. This study reveals that non-Aspergillus fungi like Drechslera, Exserohilum, and Bipolaris are likely culprits, emphasizing the need for fungal cultures.
Area of Science:
- Mycology
- Immunology
- Otolaryngology
Background:
- Allergic fungal sinusitis (AFS) diagnosis traditionally relies on morphology in tissue, often leading to Aspergillus attribution.
- Fungal cultures are infrequently performed in AFS cases, limiting definitive identification.
- This study challenges the predominant Aspergillus hypothesis in AFS.
Observation:
- Three patients (ages 11, 16, 43) presented with AFS.
- Histopathology showed fungal elements resembling Aspergillus.
- Nasal secretion cultures identified non-Aspergillus species: Drechslera, Exserohilum, and Bipolaris.
Findings:
- Non-Aspergillus fungi are a significant cause of allergic fungal sinusitis.
- Fontana-Masson staining supports the identification of non-Aspergillus fungi.
- Histopathology alone can be misleading in AFS diagnosis.
Implications:
- Accurate fungal identification through tissue culture is crucial for AFS diagnosis.
- Fontana-Masson staining serves as a valuable diagnostic tool when cultures are negative or unavailable.
- Rethinking the etiology of AFS is necessary, moving beyond Aspergillus as the sole causative agent.