A 45-year-old diabetic patient presents with proptosis, complete ophthalmoplegia and cavernous sinus thrombosis 5 days after developing nasal pain. MRI shows soft tissue infiltration of the pterygopalatine fossa. The most likely diagnosis and causative organism are:

• A Acute invasive fungal rhinosinusitis — Rhizopus/Mucor species ✓
• B Rhinosinusitis — Aspergillus fumigatus
• C Bacterial orbital cellulitis — Staphylococcus aureus
• D Allergic fungal sinusitis — Alternaria species

Explanation

This scenario describes acute invasive (fulminant) fungal rhinosinusitis, classically caused by Mucorales (Rhizopus, Mucor, Cunninghamella) in diabetic or immunocompromised patients. The characteristic features include rapid orbital spread (proptosis, ophthalmoplegia), cavernous sinus thrombosis, and pterygopalatine fossa involvement due to angioinvasion. Aspergillus can cause invasive disease but is more common in haematological malignancy. Allergic fungal sinusitis is non-invasive and occurs in immunocompetent atopic individuals.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.