Invasive Fungal Sinusitis

Invasive fungal sinusitis (IFS) is an angioinvasive infection of the paranasal sinuses by hyaline molds, primarily Mucorales (Rhizopus, Mucor, Lichtheimia) causing mucormycosis, and Aspergillus species. It is a medical and surgical emergency in immunocompromised patients with mortality of 30–60% even with optimal management. Acute invasive fungal sinusitis must be distinguished from chronic invasive and granulomatous forms which run more slowly and occur in immunocompetent hosts.

Risk groups include diabetic ketoacidosis (classical mucormycosis), hematologic malignancy with prolonged neutropenia, allogeneic stem cell transplant with GVHD, solid organ transplant on heavy immunosuppression, deferoxamine therapy (specifically for mucormycosis due to iron utilization), HIV with CD4 < 50, and severe COVID-19 with corticosteroid therapy (post-COVID mucormycosis).

Clinical hallmarks are facial pain, periorbital edema, black eschars on palate or turbinate, ophthalmoplegia, vision loss, and cranial nerve palsies indicating intracranial extension. Diagnosis combines clinical suspicion, nasal endoscopy with biopsy showing broad non-septate hyphae (Mucorales) or septate acute-angle branching hyphae (Aspergillus), histopathology with angioinvasion, and culture (frequently negative). Imaging with MRI brain and orbits and CT sinuses delineates extent. Management is multidisciplinary: aggressive surgical debridement, lipid formulations of amphotericin B (5–10 mg/kg) for mucormycosis, isavuconazole or voriconazole for aspergillosis, reversal of immunosuppression, and correction of acidosis.