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Evaluating Allergic Fungal Rhinosinusitis (ARFS): Symptoms & Diagnostic Criteria

Author Julia Casazza covers Evaluating Allergic Fungal Rhinosinusitis (ARFS): Symptoms & Diagnostic Criteria on BackTable ENT

Julia Casazza • Nov 28, 2023 • 90 hits

Allergic fungal rhinosinusitis (AFRS) is a subset of chronic rhinosinusitis with nasal polyps (CRSwNP) that classically affects young adults living in the Southern United States. However, recent basic science and epidemiological research targeting AFRS reveals that the scope of this disease is broader than initially expected. Allergic fungal rinosinusitis symptoms consist of anosmia, facial pain/pressure, purulent mucoid drainage, and nasal obstruction/fullness. Rhinologist and AFRS expert Dr. Amber Luong recently collaborated with BackTable to share her expertise. Interested in learning about the pathophysiology, presentation, and workup of AFRS? Keep reading.

This article features excerpts from the BackTable ENT Podcast. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.

The BackTable ENT Brief

• Allergic fungal rhinosinusitis is a subset of CRSwNP that is characterized by thick, eosinophilic mucus resembling “peanut butter.” In long standing cases, presence of this mucus may cause the sinus cavities to expand, distorting their anatomy.

• Patients with AFRS are often in their late teens or twenties – older than cystic fibrosis patients, but younger than other CRSwNP patients. As AFRS is a reaction to environmental fungi, they may report comorbid allergic rhinitis.

• Historically, the Bent & Kuhn criteria were used to diagnose AFRS. These criteria require a clinical exam, history, and CT scan findings consistent with the disease. Given contemporary research on AFRS in colder climates, Dr. Luong recommends that otolaryngologists interpret these criteria within their clinical context.

• Labs are not required to diagnose AFRS, however, elevated total IgE is characteristic of this condition and bolsters the case for diagnosis.

Evaluating Allergic Fungal Rhinosinusitis (ARFS): Focus on Symptoms & Diagnostic Criteria

Table of Contents

(1) What is Allergic Fungal Rhinosinusitis?

(2) Who is the Typical Allergic Fungal Rhinosinusitis Patient?

(3) How to Differentiate Allergic Fungal Rhinosinusitis: Diagnostic Criteria & Environmental Considerations

(4) Imaging for Allergic Fungal Rhinosinusitis

(5) Using Labs & Allergy Testing to Complete the Clinical Picture

What is Allergic Fungal Rhinosinusitis?

Allergic fungal rhinosinusitis is a special kind of chronic rhinosinusitis with nasal polyps (CRSwNP). Patients with AFRS meet diagnostic criteria for CRSwNP but additionally have findings specific for AFRS. These findings include thick eosinophilic mucus resembling “peanut butter,” sinus cavity expansion (visible on CT, or in severe cases, on physical exam), and elevated IgE. Though the pathogenesis of AFRS remains an active area of research, it likely occurs when environmental fungal spores enter the nasal cavities of patients with genetic proclivity for inflammation.

[Dr. Amber Luong]
Allergic fungal rhinosinusitis is basically a subtype of the bigger chronic rhinosinusitis with nasal polyps. We have chronic rhinosinusitis with and without nasal polyps. When we start looking at the nasal polyp group, allergic fungal falls under that. The reason why it's been carved out is because of some of the unique features of this disease. Some of which includes sometimes such severe presentation that the sinus cavities are so expanded that you get these really impressive CT scans where the frontal sinus is expanded into the intracranial cavity, not necessarily invading it like you alluded to, but more just because it's been there for so long and expanded the sinus cavity outside of its normal dimensions. It can expand into the orbital area.

Luckily, oftentimes, it's still preserved within the sinus cavity, but you get these really dramatic CT scans. Also on CT scans, you get a presence of this really thick, it's been described as “peanut butter mucin,” really sticky, thick mucin. Then these patients have an allergy sensitivity. If you did skin testing or blood testing, they do have elevated IgE level to the various different fungal antigens. The other characteristic is that when you look at the total IgE level, it's like out the roof. You see elevated IgE levels in allergy patients, but maybe in the hundreds in allergic fungal rhinosinusitis, it's in the thousands. Almost following into that category of hyper IgE syndromes such that we see in the thousands. It's a really unique phenotype and subtype of CRS with nasal polyps.

Listen to the Full Podcast

Allergic Fungal Rhinosinusitis with Dr. Amber Luong on the BackTable ENT Podcast)
Ep 73 Allergic Fungal Rhinosinusitis with Dr. Amber Luong
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Who is the Typical Allergic Fungal Rhinosinusitis Patient?

Relative to other sinusitis patients, allergic fungal rhinosinusitis patients tend to be younger, with many presenting in their twenties, though childhood disease is not uncommon. Patients will complain of allergic fungal rhinosinusitis symptoms such as anosmia, facial pain/pressure, purulent mucoid drainage, and nasal obstruction/fullness. Dr. Luong notes that the slow, steady onset of AFRS in many patients might lead them to underestimate their symptom burden. Disease involvement is most often unilateral, differentiating it from cystic fibrosis (another cause of sinusitis in teenagers and young adults).

[Dr. Gopi Shah]
Thank you for clarifying that. I think it would be helpful to take a step back now and think about how these patients present. What are they looking like when they walk into your clinic?

[Dr. Amber Luong]
Yes, so the whole spectrum. What's interesting about allergic fungal is that they can present quite young. Our typical CRS with nasal polyps, I think would present probably around 30s to 50 years of age. In allergic fungal, you should become more alert to a possible allergic fungal rhinosinusitis when you see a young person in their 20s. The youngest person that I saw present with allergic fungal is age 6. Very uncommon, but it can happen. It's not uncommon to see late teenage years and early 20s. They present with unilateral disease. Unlike another group of polyp patients in younger kids is cystic fibrosis.

You look at the patient and they're like, yes, I've got a little bit of a headache and a stuffy nose. You're like, oh my goodness. Yes, so very low symptom burden polyps that can sometimes present on both sides or just on one side. Those are some of the highlights from that disease presentation.

[Dr. Gopi Shah]
Yes, I totally agree. Bulk of my kids were probably between 12 to 16 when they would present. Usually, they came in and nobody's ever asked them if they could smell and they'll tell you, "Oh, I haven't smelled in years." The biggest one was, and they may or may not have even noticed it, and they're there with family, is the proptosis or just some sort of asymmetry. There's always, not always, I'd say maybe 50%. Those are probably my 14-year-old adolescent, mostly males, with some sort of proptosis. Although every once in a while I'd see it. Youngest mine, I think, was six. That was a tough one because the workup was so indolent. You don't expect AFS. Their steroid response was a little bit more of where all of a sudden it was gone. They didn't have as much time to maybe develop all that peanut butter mucin, and you're working them up for CF, PCD, they have this throat clearing, maybe some cough. The younger they are, it can be a vaguer presentation because there's a lot more to think about. I agree that the allergic fungal rhinosinusitis symptoms are mild and finally, they just can't breathe or their mouth breathing or, and it's been going on for a long time and by the time they come up to you.

How to Differentiate Allergic Fungal Rhinosinusitis: Diagnostic Criteria & Environmental Considerations

Historically, diagnosis of allergic fungal rhinosinusitis required patients to meet criteria for CRS, plus an additional five diagnostic criteria proposed by Bent & Kuhn. These criteria include: nasal polyps, eosinophilic mucin, type 1 fungal hypersensitivity, characteristic CT findings, and a positive fungal stain. Given the strong environmental influence on disease presentation in patients with AFRS, Dr. Luong advocates flexibility when using the Bent & Kuhn criteria to diagnose. Patients in colder climates, where fungal spore levels fluctuate greatly with seasons, may not present with classic “peanut butter” eosinophilic mucus though their presentation otherwise aligns with AFRS.

[Dr. Gopi Shah]
When you diagnose it, can you pretty much diagnose it then on CT or are you then in your workup checking off the-- are we still doing the Bent & Kuhn Criteria or how do you actually diagnose it clinically? Are you just looking at the scan and then look in the nose, if you see some peanut butter and you're like, Oh, that's probably AFS or are there certain things in your checklist that you want to make sure that you have?

[Dr. Amber Luong]
Yes, great question. Actually, the Bent & Kuhn Criteria has been a great criteria for us to make this diagnosis. One of those is, the nasal polyps we talked about, the eosinophilic mucin, CT changes, but it turns out that the more we are starting to talk as a community, a worldwide community, where we're starting to realize that there are several patients that you can check mark and meet them at Bent & Kuhn Criteria, but it either has a different presentation in different geographic locations or they're totally different things. It's confusing because in the South where we live, in the Southern regions, you get that classic allergic fungal, exactly what we talked about, this thick peanut buttery mucin, the fungal allergies, the expanded CT scans, but then when I talk to my colleagues, let's say in Canada, where they make the diagnosis of allergic fungal, they may have the fungal-specific IgE elevation, so a fungal allergy, but they don't get the same expanded CT scans.

They don't get the same really thick peanut butter, although they do get some sort of eosinophilic mucin. The question is whether or not these are the same diseases. I think those of us in the south that see the classic ones, I would say that it's probably going to turn out to be different than what they see up north, which is more of an eosinophilic serous with nasal polyps. I don't know if that's going to make any difference right now.

[Dr. Gopi Shah]
I wanted to ask about, do we know why there's that geographic difference? Does it just have to do with certain fungi being in certain places like in the south that aren't up north? Does it just have to do with that part of the environment? But then now I also want to make sure that we touch on endotypes and expand on that as a definition. I don't know what would makes sense to cover first.

[Dr. Amber Luong]
Yes, so, great questions! In terms of geographic distribution, we believe, so this was described many years ago by another fantastic woman rhinologist, Dr. BJ Ferguson. She was the lead author on this paper that talked about the geographic distribution of allergic fungal rhinosinusitis. It turns out that you do get much higher level of prevalence of AFRS in the south. I don't know if we know exactly why we do get this geographic distribution, but it sort of supports the concept that there is an environmental trigger to this disease process. That there must be an underlying genetic defect. Otherwise, everyone in the south would get it. There also must be a geographic, maybe the levels of fungus more than the actual presence of specific fungi, because a lot of these are very much prevalent everywhere. Staph aureus, similarly. Fungus, the different species are actually quite prevalent in most places. It's just that in the south where it's hot and humid, the duration of the year where you get these high levels of fungus is going to be longer than, let's say, in the north where you get these very distinct seasons and so you get a really cold front, so it kills all these spores while in Houston, we're happy if we get two weeks of where it drops into the 30s. Probably similar to Dallas, although it gets a little bit colder there. I think that's why we're seeing some of this distribution. Also, you'll see the distribution closer to like in the US around the Mississippi Basin.

There it's, again, humid, more prevalence, and higher loads of fungus. I think allergic fungal is unique in that it does really highlight this environmental component along with the probably genetic component of chronic rhinosinusitis more so than other endotypes.

Imaging for Allergic Fungal Rhinosinusitis

CT sinus without contrast is the only imaging study needed for most cases of allergic fungal rhinosinusitis. CT will show sinus opacification of various densities (indicating eosinophilic mucus) and polyps. Disease is most often unilateral. Sinus cavity distortion and thinning of bone are present in an appreciable minority of patients. MRI is indicated in cases of complications (meningitis, vision loss), cranial nerve deficits on exam, or possible malignancy.

[Dr. Gopi Shah]
That brings me to the question of imaging. Is there ever a role for CT with contrast or an MRI? Now, we talk about these really impressive CAT scans and like you said, if it's that anterior cranial fossa super pushed up or super thinned out and whatnot, MRI though, you tell me, because I always go back and forth. I'm like, would I go in if I think it's probably going to be fine, but then I'm like, do I need to be getting it? I feel like I should know, but I don't.

[Dr. Amber Luong]
I think when I was earlier in my career, I would get the MRIs. But after the experience with it, more often than not, it's not an issue. I don't normally get an MRI because it's so much more difficult to get the MRI. If I'm going to get the MRI, it's usually with contrast. Again, it's just so much more challenging to get the MRI. Luckily in a majority of cases, you won't have that concern about the separation. I would say if you don't see a lot of allergic fungal or you don't get that opportunity where you see them, I would tell you to get the MRI at least from time to time, just because it's quite impressive seeing the drop signal on the MRI, some of these characteristics, and just to sort of give you comfort going forward to not have to get the MRI, just to be able to see that. I don't get it now on a regular basis unless there's something in their history, i.e. vision loss or meningitis, which thank God, it doesn't happen very often.

If there's some other complications such as that, then I'll get the MRI, or because of some other issue, I am concerned about a prolapse or a loss of the integrity of the skull base or the orbit, then I may get the MRI, but most of the time, I don't.

[Dr. Gopi Shah]
I agree with that. I think unless there's a cranial nerve, something on my physical exam, which I've seen with expansion, or I'm not 100% sure clinically that this is what I'm dealing with, that I may get it.

Using Labs & Allergy Testing to Complete the Clinical Picture

Allergic fungal rhinosinusitis can be diagnosed based on history, physical, and sinus CT. However, additional labs can increase confidence in this diagnosis and identify comorbid conditions exacerbating disease burden. Since AFRS is an eosinophil-driven process, total IgE will be elevated, though serum eosinophils will be normal. Radioallergosorbent (RAST) testing identifies environmental allergens potentially augmenting allergic fungal rhinosinusitis symptom burden.

[Dr. Ashley Agan]
Yes, for sure. Other than imaging, do you get any other testing? Do you get labs where you're checking IgE levels? Do you always culture the peanut butter, thick eosinophilic mucin? What else is part of the workup?

[Dr. Amber Luong]
Yes, so at least in the South, and you probably see this, I don't do as much imaging, not much workup anymore because it's such a classic presentation. When I was starting out and trying to really understand this disease, I would get eosinophil levels, CBC with diff, and I still would get those in my fungal panel. I want to get a total IgE level. I do want to confirm that there's fungal hypersensitivity, and oftentimes it will be, especially here where it's much more classic presentation, so it's almost so obvious, but we do want to get that just to confirm it. Then a CBC with diff, however, in these patients, typically their serum eosinophil levels is normal.

[Dr. Ashley Agan]
In my workup, I tend to, I'll get RAST. A lot of times they've already come in. Some of the patients who have already come in with allergy testing, whether it's skin or RAST. Sometimes on the way out, I'll just have them get a RAST panel, but I don't always know exactly what I'm looking for. I just want to have that sort of type one hypersensitivity and make sure there is some sort of mold or fungus that they're allergic to. I think I need to be a little bit more thoughtful about, maybe incorporating, like I never usually check eosinophil levels or IgE levels routinely.

Podcast Contributors

Dr. Amber Luong discusses Allergic Fungal Rhinosinusitis on the BackTable 73 Podcast

Dr. Amber Luong

Dr. Amber Luong is the vice president of the American Rhinology Society and a professor of otolaryngology at McGovern Medical School in Houston, Texas.

Dr. Ashley Agan discusses Allergic Fungal Rhinosinusitis on the BackTable 73 Podcast

Dr. Ashley Agan

Dr. Ashley Agan is a practicing ENT and assistant professor at UT Southwestern Medical Center in Dallas, TX.

Dr. Gopi Shah discusses Allergic Fungal Rhinosinusitis on the BackTable 73 Podcast

Dr. Gopi Shah

Dr. Gopi Shah is a practicing ENT at UT Southwestern Medical Center in Dallas, TX.

Cite This Podcast

BackTable, LLC (Producer). (2022, October 11). Ep. 73 – Allergic Fungal Rhinosinusitis [Audio podcast]. Retrieved from

Disclaimer: The Materials available on are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.



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