Allergic Fungal Sinusitis

Abstract

Allergic fungal sinusitis (AFS) is a newly recognized form of sinusitis characterized by opacification of the paranasal sinuses by "allergic mucin" (AM) admixed with scattered fungal organisms. AM consists of necrotic, or partially necrotic, eosinophils and Charcot-Leyden crystals suspended in lakes of laminated, mucinous material. AFS is characterized by the absence of bone or soft tissue invasion, purulent exudate or granulomatous inflammation. Clinically, it is important to differentiate AFS from both acute invasive fungal sinusitis and noninvasive mycetoma because the three diseases are treated with different modalities and have different prognoses. Although the radiologic features of AFS are often characteristic, occasionally it may be difficult to exclude neoplasia. Two cases of AFS, in which intraoperative diagnosis was made on the basis of the presence of both AM and fungal organisms, are reported. Cytologic diagnosis of AFS can be made from intraoperative sinus aspirates from the presence of AM and fungal elements. AM and fungi provide presumptive evidence for a noninvasive, allergic fungal disease and can help reassure clinicians intraoperatively and guide clinical management.