Nasal cavity, paranasal sinuses, nasopharynx
Infectious lesions
Allergic fungal sinusitis
Last author update: 1 March 2016
Last staff update: 12 August 2022
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PubMed Search: Allergic fungal sinusitis [title] nasal
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Pathophysiology | Clinical features | Laboratory | Radiology description | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosis | Additional referencesCite this page: Sun J. Allergic fungal sinusitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/nasalallergicfungal.html. Accessed April 18th, 2024.
Definition / general
- Chronic allergic fungal sinusitis is an eosinophil mediated hypersensitivity reaction initiated by environmental fungi
Essential features
- Characterized by thick allergic mucin (with degranulated eosinophils and Charcot crystals) and hyphal fragments on GMS stain
Terminology
- Also called allergic fungal rhinosinusitis
Epidemiology
- 5 - 10% of all cases of chronic sinusitis (Am J Surg Pathol 1983;7:439)
Sites
- Multiple; nasal cavity or paranasal sinuses
Pathophysiology
- Environmental causes
- A. fumigatus, A. flavus or demateaceous fungi can trigger extreme eosinophil driven hypersensitivity to fungi in susceptible individuals
- Allergic fungal sinusitis is a TH 2-like lymphocyte mediated response
Clinical features
- Young adult with recurrent sinonasalpolyp, asthma, poor response to medical treatment
Laboratory
- Peripheral eosinophilia, elevated IgE
Radiology description
- CT: opacification of the nasal cavity and one or more paranasal sinuses
- Erosion of bone (skull base and orbit) is seen in 20 - 60% of cases
Case reports
- 24 year old woman with allergic bronchopulmonary aspergillosis with obstruction of the upper respiratory tracts (Chest 1976;70:788)
- Pathologic findings in allergic aspergillus sinusitis (Am J Surg Pathol 1983;7:439)
- Allergic aspergillosis of the maxillary sinuses (Thorax 1981;36:707 (abstract))
Treatment
- Complete endoscopic removal of the mucus and inflamed tissue followed by intranasal or systemic corticosteroids and possible maintenance therapy with fungal desensitization vaccines
Gross description
- Edematous polypoid respiratory mucosa with thick, tenacious mucus similar to peanut butter or wet clay
Gross images
Contributed by Margie Brandwein-Gensler, M.D.
Allergic fungal rhinosinusitis
Microscopic (histologic) description
- Diagnostic features: eosinophilic mucin with red and blue ripples (laminations composed of cellular debris, epithelium, polymorphonuclear cells, degranulated eosinophils and Charcot Leyden crystals)
- Charcot Leyden crystals are pink/red refractive, and form long needle-like structures
- Rare noninvasive fungal hyphae (often found only with GMS stain)
- Schneiderian mucosa reveals thickened basement membrane with goblet cell hyperplasia, and numerous inflammatory cells with prominent eosinophils
- Eosinophils may have degenerative changes of smudged, elongated or basophilic nuclei
Microscopic (histologic) images
Contributed by Kelly R. Magliocca, D.D.S., M.P.H.
Eosinophilic mucin associated with allergic fungal sinusitis
Charcot-Leyden crystals
Grocott-Gomori methenamine silver
Contributed by Margie Brandwein-Gensler, M.D.
Eosinophilic mucin
Fungal detection
Differential diagnosis
- It is unclear if eosinophilic mucin rhinosinusitis (EMRS) is a distinct entity from allergic fungal sinusitis (AFS) because:
- Fungal hyphae are not always detected in allergic mucin, although the sensitivity for fungal detection by the gold standard Gomori methanamine silver (GMS) stain is dramatically improved by trypsin predigestion, which speaks against EMRS as a distinct entity
- On the other hand, aspirin sensitivity and bilateral sinus disease are more common types of eosinophilic mucin rhinosinusitis than allergic fungal sinusitis, consistent with the idea that ERMS represents a distinct clinical entity
- Thus, this issue remains unresolved
