Nasal cavity
Inflammatory / infectious lesions
Allergic fungal sinusitis

Author: Jihong Sun, M.D. (see Authors page)
Editor: Margie Brandwein-Gensler, M.D.

Revised: 13 April 2016, last major update March 2016

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Allergic fungal sinusitis [title] nasal

Cite this page: Allergic fungal sinusitis. website. Accessed October 23rd, 2016.
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
  • Also called allergic fungal rhinosinusitis
  • Multiple; nasal cavity or paranasal sinuses
  • 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
  • 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% to 60% of cases
Case Reports
  • Complete endoscopic removal of the mucus and inflamed tissue followed by intranasal or systemic corticosteroids and possible maintenance therapy with fungal desensitization vaccines
Clinical Images
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Allergic fungal sinusitis

Gross Description
  • Edematous polypoid respiratory mucosa with thick, tenacious mucus similar to peanut butter or wet clay
Gross Images
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Courtesy of Margie
Brandwein-Gensler, M.D.

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Allergic fungal rhinosinusitis, thick mucin,
often described as similar to peanut butter or wet clay.

Micro 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
Micro Images
Images hosted on PathOut server:

Courtesy of Margie Brandwein-Gensler, M.D.

Image hosted on Other server:

Allergic mucin

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