Severe pan sinus mucosal thickening and the "double density" appearance to the mucosal thickening indicates a non-invasive fungal sinusitis.

Differential diagnosis:

• allergic fungal sinusitis (AFS): is the most common form and involves multiple paranasal sinuses with centrally hyperdense content on CT
• paranasal sinuses mycetoma: usually only involves the maxillary sinus and ethmoid and frontal sinuses are less commonly affected. Soft tissue density with/without calcification is a diagnostic feature on CT