|Year : 2017 | Volume
| Issue : 2 | Page : 43-46
Fungal vs non-fungal allergic mucin rhinosinusitis
Ibrahim Sumaily1, Majed Assiri1, Ali Alzarei2
1 Resident, Department of Otolaryngology, Head and Neck Surgery, Asir Central Hospital, Saudi Arabia
2 Consultant, Department of Otolaryngology, Head and Neck Surgery, Asir Central Hospital, Saudi Arabia
|Date of Web Publication||7-Jan-2020|
Department of Otolaryngology Head and Neck Surgery Asir Central Hospital
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sumaily I, Assiri M, Alzarei A. Fungal vs non-fungal allergic mucin rhinosinusitis. Saudi J Otorhinolaryngol Head Neck Surg 2017;19:43-6
|How to cite this URL:|
Sumaily I, Assiri M, Alzarei A. Fungal vs non-fungal allergic mucin rhinosinusitis. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2017 [cited 2022 Nov 28];19:43-6. Available from: https://www.sjohns.org/text.asp?2017/19/2/43/275314
| Introduction and Definitions|| |
Sinonasal polyposis is a common clinical finding of various risk factors. The exact cause and mechanism of polyps formation are not known yet. Allergic fungal sinusitis (AFS) is a type I hypersensitivity reaction to fungal antigens in which patients usually present with unilateral or bilateral nasal polyps . It was first reported as a distinct clinical entity in 1976 . The disease consists of two parts; the presence of fungus and the immune response. The fungal infection should be non-invasive to be labeled as allergic fungal rhinosinusitis . Up to date no consensus exists among rhinologists concerning diagnostic criteria for allergic fungal sinusitis (AFS) ,. Bent and Kuhn described what probably is the most widely accepted criteria for diagnosis . Ferguson 2000,  proposed the use of the term eosinophilic mucin rhinosinusitis (EMRS) when the mucin is devoid of identifiable fungus . However it is uncommon to find a patient labeled with entity, and most of those who have fulfilled some of the Bent and Kuhn criteria are being labeled as AFS.
The incidence of diagnosis of Allergic Fungal Rhinosinusitis (AFS) is noticed to be overestimated. One of the causes is that the patients are labeled with this entity depending on clinical impression based upon:
- Computed-Tomography (CT) criteria of AFS.
- Mucin presence intra-operatively.
- Ignoring the final histopathology result.
The aims of this study was to evaluate the applicability of the Bent and Kuhn diagnostic criteria on those patient who have been labeled as AFS.
| Methodology|| |
This was a retrospective study. We reviewed the records of 223 patients who underwent endoscopic sinus surgery between 2012-2016 for chronic sinus pathology being labeled as AFS. We evaluated them for the AFS- diagnostic criteria availability and applicability. Our inclusion criteria were those patients who were labeled as AFS preoperatively, presence of nasal polyposis and allergic mucin. We excluded revision cases, those with incomplete aata, tnose aiagnosea as lungal ball, tnose diagnosed as invasive fungal sinusitis, those diagnosed as neoplastic disease, and those with no fungal stains being used.
Out of 223 patients, 93 met our inclusion criteria, and the rest were excluded. We divided them into 2 groups:
- Those who had confirmed diagnosis of AFS by histopathological presence of fungal hyphae and allergic mucin.
- Those with allergic mucin without fungal hyphae presence.
We then compared the two groups and tried to focus on the differentiation between these two entities, and aided our results with comparative literature review. SPSS v22 was used for data analysis.
| Results|| |
The applied diagnostic criteria included atopy 97%, polyps 100%, CT Criteria of AFS 65.6%, unilateral disease 29%, eosinophilia mucin without invasion 100%, and fungus on histopathology 19.4%.
The presence of fungus on histopathology samples was positive in 18 out of 93 (19.4%). cases labeled as AFS pre operatively. Sixteen (88.9%) of them fulfilled the other criteria as well. This was the most sensitive and specific distinct criterion. The CT criteria of AFS alone found to be highly sensitive (94.4%) but less specific (58.6%) for AFS [Figure 1] and [Figure 2]. Eosinophilic mucin [Figure 3] is found to be very sensitive (100%) criterion but not specific (19.4%). Eosinophilic Mucinic rhinosinusitis found to be the most common cause of criteria of AFS on CT images of those patient who were preoperatively labeled as AFS [Table 1]. Both AFS and EMRS found to be bilateral almost equally in same high percentage of cases, 72.2% and 70.7% respectively [Table 3]. This indicated that unilateral disease is not a criterion for both disease entities.
|Figure 1: The CT Criteria of AFS among those with AFS in comparison to those with EMRS.|
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|Figure 2: Samples of CT scans of those patient with double density and other criteria of AFS and are labled as ASF and finally found to have no fungal component in their disease.|
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|Figure 3: This allergic mucin was looking intraoperatively the same in both AFS and EMRS.|
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|Table 3: The Bent and Kuhn Criteria fulfillment found to be very useful in the diagnosis of AFS with overall sensitivity of 94.4% and specificity of 98.7%|
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The used clinical impression in diagnosing these cases and labeling them as AFS was associated with poor positive predictive value (19.4%). While the Bent and Kuhn Criteria fulfillment showed 100% positive predictive value although it is less sensitive (88.9%) than the clinical impression (100%) [Table 2].
| Discussion|| |
AFS is a common diagnosis encountered by otorhino- laryngologists on daily bases. But it is clearly noticeable that that there is over diagnosis of AFS in the clinical practice, although it seems to be less frequent in reality. EMRS is another clinical entity which resembles AFS in all aspects except the presence of fungus on histopathology slides . Up to date, no specific study encountered the differences between AFS and EMRS based on randomized clinical trials.
Lara, et al.  studied fungal versus non-fungal allergic mucin sinusitis retrospectively on 25 cases and found that there is no differences in the clinical presentation of the two groups. The radiological findings and intraoperative findings were identical among the two groups. But histopathologically the mucin was apparent on the hematoxylin-eosin–stained sections of the group with fungi, though Charcot crystals were present in both groups. And as a conclusion of their study they said AFS is more appropriately termed allergic mucinous sinusitis or eosinophilic mucinous rhinosinusitis .
In the literature, in Saudi Arabia, only 3 studies tackled the AFS diagnostic criteria. Two of them were mainly concerned about the prevalence in adult and in pediatric, populations and the third study tackled the radiological and microbiological features ,,. Our study is the first study tackling the EMRS in comparison to AFS in Saudi Arabia.
In our study, the clinical presentation was almost the same, with both groups equally having atopy, though it was relatively more in AFS cases. Also nasal polyposis was present in both groups. The CT criteria of AFS were not specific, though sensitive, for AFS, as it was present in most of those with EMRS. The presence of eosinophilic mucin is not specific for AFS. The gray- brownish material found in those with double density on their CT is mainly tissue debris and accumulated crustations and thick secretions (mucin), not a fungus accumulation. The positive histopathology sample for fungus is the most specific criterion, but it should be aided with other highly suggestive criteria, especially CT criteria of AFS and eosinophilic mucin. Most of those who were labeled as AFS preoperatively based on clinical suspicion and radiological finding were found to be EMRS, not AFS.
The used clinical impression in diagnosing these cases and labeling them as AFS was very sensitive (100%) but has a poor positive predictive value of 19.4%. While the Bent and Kuhn Criteria fulfillment found to be very useful in the diagnosis of AFS with overall sensitivity of showed less sensitivity (88.9%) but has a very high positive predictive value (100%).
| Conclusion|| |
The diagnosis of AFS is complementary and the patient should not be labeled with this entity preoperatively. There is over-diagnosis of AFS based on clinical impression. The management of these cases with such inappropriate diagnosis was not significantly affecting the final outcome. The most sensitive and specific diagnostic criterion is the presence of non-invasive fungal hyphae on histopathology. Other very sensitive, but not specific, diagnostic criteria for AFS include allergic mucin and polyps, and, to less extent, the CT criteria of AFS. Further studies on the differences between the mucin in those with AFS and those with EMRS and the role of the fungus in the disease process are recommended as it seems that it is just an entrapped material with the secretions rather than being an integral part of the pathology.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]