Immunologic testing for allergens
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RAST versus skin testing
Patients with allergic fungal sinusitis (AFS) generally demonstrate positive skin tests and in vitro (RAST) responses to fungal and nonfungal antigens. Manning et al, who compared 16 patients with histologically confirmed allergic fungal sinusitis (AFS) with a control group of patients with chronic rhinosinusitis, first demonstrated the sensitivity of RAST. Levels of fungal-specific IgE were uniformly elevated in all patients with allergic fungal sinusitis (AFS) and corresponded to the results of fungal cultures. In contrast, levels of fungal-specific IgE were not elevated within the control group. Moreover, patients with allergic fungal sinusitis (AFS) appear to demonstrate a broad sensitivity to a number of fungal and nonfungal antigens. Mabry et al have reported their experience, which indicates that patients with allergic fungal sinusitis (AFS) are allergic to multiple fungal antigens and to many typical nonfungal antigens.
Preliminary information suggests that methods of quantitative skin testing (in vivo) may provide even greater sensitivity ratings than RAST in patients with allergic fungal sinusitis (AFS). RAST traditionally has been considered less sensitive than skin testing during the investigation of atopy involving fungi. This has been attributed to technical problems, such as difficulty in binding the mold antigen to the carrier substrate.
To study the validity of this concept, Mabry et al prospectively evaluated 10 patients with allergic fungal sinusitis (AFS) for sensitivity to 11 pertinent fungi by both RAST and dilutional intradermal testing. A predictable correlation between RAST and skin test scores was observed in many, but not all, patients. Most often, this disparity was in the form of greater sensitivity indicated by skin testing than by RAST, sometimes differing by as many as 3 classes.
The lack of concordance was not confined to testing for fungi cultured from the sinuses, nor was it more or less pronounced in the case of dematiaceous fungi. The most likely causes for the disparity were thought to involve subtle differences in antigens used in skin test material as compared to RAST standards. Additionally, skin testing allowed observation of delayed and late-phase reactions, a measure not possible by specific IgE testing with RAST. This study appears to emphasize the importance of both skin testing and specific IgE testing via RAST in initial evaluation of patients in whom allergic fungal sinusitis (AFS) is suspected.
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Left middle meatus with suctioning of thick allergic mucin from the ethmoid bulla in the center of the picture; the end of the suction is in the inferior portion of the picture.
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The viscosity of a thick allergic mucin being suctioned from the nasal cavity and vestibule in a patient with allergic fungal sinusitis.
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View just inside the nasal vestibule showing diffused polyposis extending into the anterior nasal cavity and vestibule; the septum is on the right, and the right lateral vestibular wall (nasal ala) is on the left. The polyps all are in the center. The polyps almost hang out of the nasal vestibule.
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A 15-year-old boy with allergic fungal sinusitis causing right proptosis, telecanthus, and malar flattening; the position of his eyes is asymmetrical, and his nasal ala on the right is pushed inferiorly compared to the left.
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A 9-year-old girl with allergic fungal sinusitis displaying telecanthus and asymmetrical positioning of her eyes and globes.
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Coronal CT scan showing extensive allergic fungal sinusitis involving the right side with mucocele above the right orbit and expansion of the sinuses on the right.
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Typical view of a middle meatus in a patient with allergic fungal sinusitis with expansion of the ethmoid complex and extension of the middle turbinate more inferiorly. This is a postoperative view.
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Coronal CT scan showing typical unilateral appearance of allergic fungal sinusitis with hyperintense areas and inhomogeneity of the sinus opacification; the hyperintense areas appear whitish in the center of the allergic mucin.
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Coronal MRI showing expansion of the sinuses with allergic mucin and polypoid disease; the hypointense black areas in the nasal cavities are the actual fungal elements and debris. The density above the right eye is the mucocele. The fungal elements and allergic mucin in allergic fungal sinusitis always look hypointense on MRI scanning and can be mistaken for absence of disease.
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Immediate postoperative 30° angled view showing the complete removal of polyps with a widened frontal sinus recess superiorly and widened ethmoid cavity in the mid portion. The middle turbinate is on the right, pushed against the septum. The lateral nasal wall is on the left.
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Fungal ball in the right maxillary sinus.
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Fungal debris being removed from the ethmoid complex. A suction device is seen in the right lower corner of the picture.
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Allergic mucin, fungal debris, and polyps are shown after removal from the patient. The scale is in inches.
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Coronal CT scan showing the postoperative view following removal of disease after significant disease recurred on both the right and left sides of the nasal cavity and sinuses; mild mucosal thickening of all involved sinuses is present, with some moderate thickening of the left maxillary sinus. All disease, even the lateral mucocele, was removed or drained endoscopically.
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Two-week postoperative endoscopic picture showing polypoid thickening already in the ethmoid cavities while the patient was still on tapering steroids; on the left is the lateral nasal wall. The right shows the middle turbinate next to the septum.
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A polypoid recurrence in the center of the ethmoid cavity. The septum is on the left.
