Diagnosis of Allergic Fungal Sinusitis

Abstract

Allergic fungal sinusitis is a noninvasive disease first recognized approximately one decade ago. It accounts for approximately 6% to 8% of all chronic sinusitis requiring surgical intervention and has become a subject of increasing interest to otolaryngologists and related specialists. Although certain signs and symptoms, as well as radiographic, intraoperative, and pathologic findings, may cause the physician to suspect allergic fungal sinusitis, no standards have been defined for establishing the diagnosis. It is extremely important to recognize allergic fungal sinusitis and differentiate it from chronic bacterial sinusitis and other forms of fungal sinusitis because the treatments and prognoses for these disorders vary significantly. To delineate a set of diagnostic criteria, we prospectively evaluated our most recent 15 patients with allergic fungal sinusitis. An allergy evaluation confirmed atopy through a strong history of inhalant mold allergies, an elevated total immunoglobulin E level, or a positive result of a skin test or radioallergosorbent test to fungal antigens in 100% of patients. All 15 patients had nasal polyposis, and 8 of 15 had asthma. There was a unilateral predominance in 13 of 15 cases. A characteristic computerized tomography finding of serpiginous areas of high attenuation in affected sinuses was seen in all patients, and 12 of 15 patients had some degree of radiographic bone erosion. Pathologic examination uniformly revealed eosinophilic mucus without fungal invasion into soft tissue; Charcot-Leyden crystals and peripheral eosinophilic were each observed in 6 of 15 patients. Every patient had fungus identified on fungal smear, although only 11 of 15 fungal cultures were positive. Therefore, for the diagnosis of allergic fungal sinusitis to be established, the following criteria should be met: (1) type I hypersensitivity confirmed by history, skin tests, or serology; (2) nasal polyposis; (3) characteristic computed tomography signs; (4) eosinophilic mucus without fungal invasion into sinus tissue; and (5) positive fungal stain of sinus contents removed during surgery. Radiographic bone erosion does not necessarily imply invasive disease, and a positive fungal culture, although desirable, is not necessary to confirm the diagnosis. Unilateral predominance of disease, a history of asthma, Charcot-Leyden crystals, and peripheral eosinophilla corroborate the diagnosis but are not always present. Perhaps because of the novelty of the disease, much misunderstanding surrounds allergic fungal sinusitis. Misdiagnosis is common, recurrence rates are high, and proper treatment remains elusive. Before proceeding with other advances, a common understanding of the diagnosis of allergic fungal sinusitis is mandatory.