Abstract
An 11-year-old white boy was referred for evaluation of severe, chronic, right-sided nasal congestion of 2 years’ duration. He had a long history of allergic rhinitis treated with immunotherapy, nasal steroids, antihistamines, and topical nasal decongestants. As the patient's nasal congestion had worsened over the previous several months, he was treated with a 10-day course of prednisone, 3 courses of oral antibiotics, and saline irrigations without significant relief.
Physical examination revealed thick bilateral nasal drainage and the presence of an allergic crease over the nasal dorsum. Nasal endoscopy demonstrated severe bilateral turbinate edema despite decongestion. In the right maxillary antrum and ethmoid bullae, thick brown mucin and polyposis were identified.
Computed tomography (CT) of the patient's sinuses showed heterogeneous opacification of the right maxillary, ethmoid, and sphenoid sinuses and the frontoethmoid recess (figure). The right lamina papyracea bowed laterally into the orbit.
The patient underwent right-sided endoscopic sinus surgery, at which time thick, rubbery material was debrided from the maxillary sinus and anterior and posterior ethmoid cavities. Postoperatively, he was treated with 6 weeks of oral steroids and topical medications, and his symptoms resolved. He resumed treatment for allergic rhinitis under the care of his allergist.
Allergic fungal rhinosinusitis (AFRS) is a noninvasive fungal sinusitis that encompasses just one arm of a wide spectrum of fungal sinus disease. AFRS is not as well described as acute and chronic bacterial sinusitis, as AFRS has only been recognized as a distinct pathologic entity during the past 3 decades.
Allergic fungal sinusitis is characterized by unilateral sinus opacification with central hyperattenuation and heterogeneous density within the sinuses.
Originally thought to arise solely from Aspergillus infection, AFRS has been shown to involve dematiaceous fungi, including Bipolaris, Curvularia, Exserohilum, and Alternaria spp, in 67% of cases. 1 These fungi are ubiquitous, and it is likely that an immunopathologic host response to fungal spores is the trigger for clinical manifestations of AFRS. The incidence of AFRS is impacted by geography, with a greater number of cases reported in warm regions with relatively high humidity. 2
Classically, a patient with AFRS will be an adolescent or young adult with manifestations of chronic sinusitis, including nasal obstruction, congestion, purulent or clear rhinorrhea, anosmia, and headache. 3 Patients are typically immunocompetent, but 63% of AFRS patients have comorbid allergic rhinitis and 53% have comorbid asthma. 2 On examination, nasal polyps and thick, yellow-green mucus will invariably be present. This inspissated allergic mucin (classically described as “peanut butter” mucus) may take the form of rubbery plugs that can be expelled from the nose. 4
Pediatric and adult patients often have differing clinical presentations. As many as 42% of pediatric patients present with alteration of their facial skeletons (proptosis, telecanthus, or malar flattening) compared to 10% for adults, which may be explained by the more pliable bony structure of children. 3 Notably, as many as 70% of pediatric patients present with unilateral disease, while 63% of adults present with bilateral disease. 3
The diagnostic criteria for AFRS developed by Bent and Kuhn 5 have been extensively modified since their introduction, but they are still widely accepted. The original criteria include type 1 hypersensitivity, nasal polyposis, eosinophilic mucus without fungal invasion into sinus tissue, a positive fungal stain of sinus contents removed at surgery, and characteristic CT findings. 5
Radiologic findings alone are often strongly suggestive of the diagnosis. CT shows opacified sinuses with central hyperattenuation from allergic mucin. As many as 60% of patients demonstrate bone erosion on the initial CT scan. The allergic mucin mass may expand to completely fill the sinus and enter the orbit or skull base. This extra-sinus extension is presumed to result from bone resorption caused by pressure from the allergic mucin. 1 Notably, tissue invasion by fungi is not present. 6
A combination of medical and surgical treatment remains the mainstay of treatment for AFRS. Surgical treatment entails the removal of all polypoid mucosa and the removal of allergic mucin that contains fungal antigens and inflammatory mediators. Although AFRS has a propensity to recur, medical treatment after surgery has been shown to decrease the recurrence rate. Systemic and topical corticosteroids and specific immunotherapy are well-supported treatment modalities in the literature. Saline irrigations, antifungal agents, leukotriene receptor antagonists, and macrolide antibiotics all may have a role in the medical management of AFRS, although their definitive roles remain unclear. 6