Nasal cavity, paranasal sinuses, nasopharynx

Infectious lesions

Allergic fungal rhinosinusitis


Editorial Board Member: Ruta Gupta, M.D.
Deputy Editor-in-Chief: Kelly Magliocca, D.D.S., M.P.H.
Bin Xu, M.D., Ph.D.

Last author update: 1 April 2025
Last staff update: 1 April 2025

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PubMed Search: Allergic fungal rhinosinusitis

Bin Xu, M.D., Ph.D.
Page views in 2025 to date: 41
Cite this page: Xu B. Allergic fungal rhinosinusitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/nasalallergicfungal.html. Accessed April 2nd, 2025.
Definition / general
  • IgE mediated allergic / hypersensitivity mucosal inflammation to noninvasive environmental fungi in immune competent patients with atopy
  • Characteristic pathologic findings are allergic mucin and the presence of fungi without tissue invasion
Essential features
  • 1 of the 3 forms of noninvasive fungal infection of the sinonasal tract; the other 2 being saprophytic fungal infestation (localized colonization) and fungal ball (Laryngoscope 2009;119:1809)
  • Characterized by thick allergic mucin (with degranulated eosinophils and Charcot-Leyden crystals) and hyphal fragments on GMS stain
  • Absence of tissue invasion by fungi
Terminology
  • Allergic fungal sinusitis
  • Eosinophil related fungal rhinosinusitis
  • Eosinophilic mucin rhinosinusitis
  • Allergic aspergillosis
ICD coding
  • ICD-10
    • J30.89 - other allergic rhinitis
    • B49 - unspecified mycosis
Epidemiology
  • 6 - 9% of all cases of chronic rhinosinusitis (Clin Rev Allergy Immunol 2006;30:205)
  • Some may have a concomitant allergic bronchopulmonary mycosis
  • Typically affects young adults with recurrent sinonasal polyps, a history of asthma and a poor response to standard medical treatments, often requiring surgical intervention
Sites
  • Nasal cavity or paranasal sinuses, unilateral or bilateral
Pathophysiology
  • Antigens released by fungi trapped in the sinus mucin stimulate production of IgE
  • Helper T cells (Th2) mediate an eosinophil rich inflammation (Clin Rev Allergy Immunol 2006;30:205)
  • Association with MHC class II HLA-DQB1*0301 and DQB1*0302
Etiology
  • The most common causal fungi are dematiaceous fungi (including Bipolaris spicifera, Curvularia lunata, Exserohilum rostratum and Alternaria alternata) and Aspergillus species such as A. fumigatus, A. flavus or A. niger (Clin Rev Allergy Immunol 2006;30:205, Med Mycol 2009;47:S324)
  • All patients are atopic with type I mediated hypersensitivity
Clinical features
Diagnosis
  • Proposed diagnostic criteria include (Otolaryngol Head Neck Surg 1994;111:580, Laryngoscope 2009;119:1809)
    • Type I hypersensitivity
    • Nasal polyposis
    • Characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings
    • Fungi identified by stains or culture
    • Pathologic findings of eosinophilic (allergic) mucin with fungal elements and no evidence of tissue invasion
Laboratory
Radiology description
  • CT: opacification of the nasal cavity and one or more paranasal sinuses, with areas of hyperattenuation (increased contrast) as a result of fungal containing allergic mucin (Clin Rev Allergy Immunol 2006;30:205)
  • Erosion of bone (skull base and orbit) is seen in 20 - 60% of cases
Radiology images

Images hosted on other servers:
Hyperattenuation areas on CT Hyperattenuation areas on CT

Hyperattenuation areas on CT

Prognostic factors
Case reports
Treatment
  • Complete endoscopic removal of all inspissated fungal containing allergic mucin and all diseased mucosa is required (Clin Rev Allergy Immunol 2006;30:205)
  • Postoperative medical management includes follow up for recurrence, in office debridement and oral or topical corticosteroid
  • Systemic antifungal treatment is not effective
Clinical images

Contributed by Kelly Magliocca, D.D.S., M.P.H.
External naris

External naris

Endoscopic Endoscopic

Endoscopic

Gross description
Gross images

Contributed by Margie Brandwein-Gensler, M.D. and Kelly Magliocca, D.D.S., M.P.H.
Peanut butter-like allergic mucin

Peanut butter-like allergic mucin

External and cut surface

External and cut surface

Microscopic (histologic) description
  • Eosinophilic mucin (allergic mucin) is diagnostic: layered appearance of mucin admixed with cellular debris, sloughed epithelium, eosinophils (some may be degranulated), Charcot-Leyden crystals and other inflammatory cells (Head Neck Pathol 2016;10:40)
  • Scanty fungal hyphae identified in 27 - 91% of cases (often found only with GMS stain) (Indian J Otolaryngol Head Neck Surg 2022;74:4640, Head Neck Pathol 2016;10:40)
  • Charcot-Leyden crystals are pink / red refractive and form long needle-like structures
  • Eosinophils may have degenerative changes of smudged, elongated or basophilic nuclei
  • No evidence of tissue invasion by fungi
Microscopic (histologic) images

Contributed by Kelly R. Magliocca, D.D.S., M.P.H. and Bin Xu, M.D., Ph.D.
Eosinophilic mucin Eosinophilic mucin

Eosinophilic mucin

Eosinophilic mucin Eosinophilic mucin

Eosinophilic mucin


Eosinophils with degranulation

Eosinophils with degranulation

Charcot-Leyden crystals Charcot-Leyden crystals

Charcot-Leyden crystals

Fungi on GMS stain

Fungi on GMS stain


GMS stain GMS stain

GMS stain

Positive stains
  • GMS and PAS stains show fungal organisms
Molecular / cytogenetics description
Sample pathology report
  • Sphenoid sinus, right, excision:
    • Consistent with allergic fungal rhinosinusitis (see comment)
    • Comment: The specimen is composed of eosinophilic mucin (allergic mucin) and strips of respiratory mucosa with chronic rhinosinusitis with eosinophilia. GMS stain shows scattered fungal organisms. The overall histologic features are consistent with allergic fungal rhinosinusitis. No evidence of invasive fungal disease is seen.
Differential diagnosis
  • Invasive fungal rhinosinusitis:
    • Tissue invasion by fungi is the hallmark for invasive fungal rhinosinusitis and is absent in allergic fungal rhinosinusitis
    • Invasive fungal rhinosinusitis most commonly impacts immunocompromised hosts, whereas allergic fungal rhinosinusitis occurs in immunocompetent patients with atopy
  • Fungal ball:
    • Fungal ball has densely packed fungal hyphae, whereas allergic fungal rhinosinusitis contains sparse fungal elements
    • Fungal ball lacks abundant allergic mucin
    • Allergic fungal rhinosinusitis and fungal ball may coexist (Laryngoscope 2009;119:1809)
Board review style question #1

A nasal biopsy of a 40 year old man is performed. The H&E and GMS stains are shown above. What is the most common cause of this disease?

  1. Candida
  2. Dematiaceous fungi or Aspergillus
  3. Histoplasma
  4. Mucor
Board review style answer #1
B. Dematiaceous fungi or Aspergillus. The pictures show allergic fungal rhinosinusitis with eosinophilic mucin on H&E and scanty fungal elements on GMS stain. The most common fungal organisms seen in this condition are dematiaceous fungi or Aspergillus. Answers A, C and D are incorrect because Mucor, Histoplasma and Candida are fungal organisms but not the most common cause of allergic fungal rhinosinusitis.

Comment Here

Reference: Allergic fungal rhinosinusitis
Board review style question #2
Which of the following statements regarding allergic fungal rhinosinusitis is true?

  1. It generally occurs in immunocompromised patients with atopy
  2. It is associated with elevated serum IgG and IgG4
  3. It is characterized by a neutrophilic rich inflammatory infiltrate in the respiratory mucosa and mucin
  4. It lacks evidence of tissue invasion by fungi
Board review style answer #2
D. It lacks evidence of tissue invasion by fungi. Allergic fungal rhinosinusitis lacks evidence of tissue invasion, which is characteristic of invasive fungal rhinosinusitis. Answer A is incorrect because allergic fungal rhinosinusitis affects immunocompetent patients with atopy. Answer C is incorrect because this entity is rich in eosinophils, not neutrophils. Answer B is incorrect because allergic fungal rhinosinusitis is associated with elevated serum IgE, not IgG or IgG4.

Comment Here

Reference: Allergic fungal rhinosinusitis
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