A 55-year-old diabetic patient on corticosteroids presents with rapid-onset facial swelling, orbital cellulitis, and black eschar over the hard palate and inferior turbinate. CT paranasal sinuses shows bony destruction of the medial orbital wall and anterior cranial fossa involvement. The most likely diagnosis and its causative organism are:
- A Acute invasive fungal rhinosinusitis — Aspergillus fumigatus
- B Allergic fungal rhinosinusitis — bipolaris/curvularia species
- C Acute invasive fungal rhinosinusitis — Mucor/Rhizopus (Mucorales order) ✓
- D Chronic granulomatous invasive sinusitis — Aspergillus flavus
Explanation
Acute invasive fungal rhinosinusitis in an immunocompromised host (diabetic ketoacidosis, neutropenia, corticosteroid use) with black eschar (angioinvasion with tissue infarction), bony destruction, and rapid orbital/intracranial extension is mucormycosis (rhinocerebral form), caused by Mucorales order organisms (Rhizopus, Mucor, Cunninghamella). Mucorales have high iron affinity in acidic pH (DKA), explaining the predilection. Allergic fungal sinusitis is non-invasive with allergic mucin; chronic granulomatous invasive sinusitis (Aspergillus flavus) is slow and seen in immunocompetent hosts.
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.