See the list below:
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Computed tomography [18]
Accumulation of allergic fungal mucin eventually leads to the increasingly well-recognized radiographic findings characteristic of allergic fungal sinusitis (AFS). Heterogeneous areas of signal intensity within paranasal sinuses filled with allergic fungal mucin frequently are identified on CT scans, as depicted in the image below.
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.
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.
See the list below:
Although these findings are not specific for allergic fungal sinusitis (AFS), they remain relatively characteristic of the disease and may provide preoperative information supportive of a diagnosis of allergic fungal sinusitis (AFS). This characteristic, which is best identified using soft-tissue algorithms on CT scan, has been the focus of some interest.
An initial theory proposed that the role of hemosiderin occurring within inspissated mucin is responsible for the areas of increased signal intensity. This was disputed by Zinreich et al, who were unable to identify increased hemosiderin within typical allergic fungal mucin. Current evidence points to the presence of accumulations of heavy metals (eg, iron, manganese) and calcium salt precipitation within inspissated allergic fungal mucin as the most likely causes of these radiographic findings. [19]
Expansion, remodeling, or thinning of involved sinus walls is common in allergic fungal sinusitis (AFS) and is thought to be caused by the expansile nature of the accumulating mucin. Areas of high attenuation are found within the expanded paranasal sinuses in all patients. Similar radiographic findings can be caused by rare osteoid/chondroid matrix-producing sinonasal sarcomas or meningiomas.
Bony erosion of the sinus walls and extension into adjacent cavities have been mentioned in many reports, usually focusing on intracranial extension, as depicted in the 1st image above. [20] In most series, a rate of approximately 20% bony erosion with extension into surrounding vital cavities is reported.
A recent review at UT Southwestern focusing on patterns of bony erosion in all the authors' patients found a 20% rate of erosion with extension. Sites of extension included the nasopharynx and pterygomaxillary space and intracranial and intraorbital areas.
A statistically significant association was identified between expansion of paranasal sinuses involved with disease and the presence of bone erosion.
The ethmoid sinus was the most commonly involved sinus, while the adjacent lamina papyracea was the most common bone to exhibit demineralization, as depicted in the image below. Extension of allergic fungal sinusitis (AFS) beyond the confines of the paranasal sinuses most commonly occurred into the orbit, followed by the anterior, middle, and posterior cranial fossae, respectively.
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.
When evaluating children and adults in the authors' population separately, no difference was observed in the amount or location of bony erosion with extension, as depicted in the Table below.
Despite the sometimes-remarkable extension into adjacent anatomic spaces, no cases of histologic invasion of fungus into the adjacent barriers of the orbital periosteum or dura of the brain were identified on histologic review.
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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.
