In ENT practice, a CT finding of hyperdense mucin with bone expansion is most suggestive of which condition?

• A. Allergic fungal sinusitis
• B. Acute bacterial sinusitis
• C. Nasal polyposis without fungal content
• D. Sinusitis with osteitis only

Answer: (A)

Recognizing allergic fungal sinusitis on CT hinges on the combination of dense, hyperattenuating mucin within the sinuses and expansion of the bony walls. The hyperdense mucin reflects fungal debris and protein-rich allergic mucin that accumulates in AFRS, which is a distinctive radiologic feature. The accumulated mucin exerts pressure over time, causing remodeling and expansion of the sinus walls; bone erosion can occur but the hallmark is expansion rather than acute destructive changes. This pattern is more specific for AFRS than other sinus conditions: acute bacterial sinusitis typically shows mucosal thickening and sometimes air‑fluid levels without dense hyperdense mucin or significant bone expansion; nasal polyposis without fungal content presents as soft tissue polyps without hyperdense material; sinusitis with osteitis emphasizes bone changes without the characteristic dense mucin.