Comparative Imaging of Allergic Fungal Sinusitis With Orbital and Intracranial Extension: A Case Report.

Allergic fungal sinusitis (AFS) is classified as a non-invasive, immunologically mediated chronic rhinosinusitis. It can rarely mimic aggressive infectious or neoplastic disease. We present two companion cases demonstrating orbital apex compression without intracranial involvement and another case with epidural extension, respectively. These cases challenge the conventional understanding of AFS and emphasize the importance of advanced imaging. We propose a novel AFS aggression spectrum (AAS) to stratify disease severity and categorize the progressive imaging features of allergic fungal sinus disease within a four-tier diagnostic framework.