Updated August 2026
When this article was first published, researchers were investigating whether new combinations of tests could help diagnose allergic fungal rhinosinusitis (AFRS) — previously often called allergic fungal sinusitis (AFS) — without relying so heavily on findings obtained during sinus surgery.
That remains an important goal, but our understanding of AFRS has developed considerably.
What is allergic fungal rhinosinusitis?
AFRS is now generally regarded as a particular form of chronic rhinosinusitis with nasal polyps (CRSwNP). It involves a strong type 2 inflammatory response associated with fungi in the sinuses. A 2026 Grand Rounds review of AFRS describes it as a distinct, non-invasive endotype of chronic rhinosinusitis with nasal polyps.
The fungi are present in the thick, eosinophil-rich mucus within the sinuses but, importantly, AFRS is non-invasive: fungal hyphae do not normally invade healthy surrounding sinus tissue.
This distinguishes AFRS from invasive fungal sinusitis, which is a very different and potentially life-threatening condition.
Why has AFRS traditionally been difficult to diagnose?
For many years, diagnosis has commonly been based on the Bent and Kuhn criteria, developed in the 1990s.
These include:
- evidence of an immediate allergic response to fungi
- nasal polyps
- characteristic changes on CT scans
- thick, eosinophil-rich mucus without fungal invasion of tissue
- fungi demonstrated within material removed from the sinuses
The difficulty is that some of the strongest evidence may only become available after sinus surgery. A 2025 contemporary review of AFRS highlights this limitation and questions the specificity and practicality of the traditional diagnostic criteria.
This led researchers to investigate whether blood tests, allergy testing, imaging and other markers could identify AFRS more reliably before an operation.
What have we learned since?
Research has continued to show that blood tests, fungal-specific IgE, eosinophils, CT imaging and other measurements can all contribute useful information.
However, there is still no single blood test or biomarker that reliably diagnoses AFRS on its own. Diagnosis continues to depend on combining clinical history, allergy and immunological findings, imaging and, where available, examination of sinus material.
At the same time, researchers have begun questioning the traditional diagnostic criteria themselves. A major multidisciplinary AFRS workshop published in 2025 brought together experts from several disciplines to review diagnosis, management, associated conditions and disease mechanisms. The group concluded that improved diagnostic criteria and better biomarkers are important priorities for future research.
AFRS is increasingly understood as a complex inflammatory condition involving interactions between fungi, the immune system and probably genetic and environmental factors. Research into the underlying biology has identified abnormalities in fungal-driven inflammatory pathways and local antifungal immune responses. A 2023 review of developments in AFRS pathophysiology and treatment discusses these mechanisms in more detail.
Has improved diagnosis reduced the need for surgery?
This was one of the hopes behind the research discussed in the original version of this article, but the picture is now more nuanced.
Surgery remains an important part of treatment for many people with AFRS.
Endoscopic sinus surgery can remove accumulated eosinophilic mucus and fungal material, remove obstructing nasal polyps, reopen affected sinuses and allow topical treatments to reach the sinus cavities more effectively.
The 2025 contemporary review describes surgery followed by topical corticosteroids and saline irrigation as the mainstay of AFRS treatment. The 2026 Grand Rounds review similarly emphasises comprehensive endoscopic sinus surgery followed by long-term topical anti-inflammatory treatment.
Medical treatment after surgery is important because AFRS has a significant tendency to recur.
What about biologic treatments?
There is increasing interest in biologic medicines that target type 2 inflammation. Some of these treatments are already used for severe asthma and chronic rhinosinusitis with nasal polyps.
A 2025 systematic review and meta-analysis of biologics in AFRS found encouraging improvements in symptoms and measures of disease activity, although the available studies were relatively small and varied considerably.
A further 2025 systematic review and meta-analysis of biologics in difficult-to-treat AFRS also found evidence of short-term benefit.
These treatments may therefore become increasingly important for selected people with recurrent or difficult-to-control AFRS, but more evidence is needed to establish exactly who benefits, when biologics should be introduced and how they fit alongside surgery and other treatments.
Why better diagnosis still matters
The objective is therefore not simply to develop a test that allows patients to avoid surgery.
Better diagnostic tools could help doctors:
- recognise AFRS earlier
- distinguish it from other forms of chronic rhinosinusitis
- identify people who need specialist assessment
- select the most appropriate treatment
- monitor disease and recurrence
- better understand which patients might benefit from newer treatments
The research described in the original article was part of an important change in thinking. Rather than viewing AFRS simply as fungal material that needs to be removed from the sinuses, we now understand it as a complex inflammatory disease associated with fungi.
Our ability to diagnose, classify and treat AFRS continues to evolve.
For a fuller explanation of fungal rhinosinusitis, its symptoms, diagnosis and treatment, see our Fungal Rhinosinusitis information page.
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