Invasive Aspergillus Sinusitis Masquerading as Hypertrophic Pachymeningitis Complicated by a Ruptured Infectious Internal Carotid Artery Aneurysm.

A 76-year-old man presented with headache, progressive left-sided visual loss, and cranial neuropathy. Initial MRI and cerebrospinal fluid findings mimicked those of hypertrophic pachymeningitis. Corticosteroid therapy provided only a transient improvement before clinical deterioration, including right-eye blindness. A re-evaluation revealed destructive sphenoid sinus disease, and surgical decompression confirmed invasive Aspergillus sinusitis. The course was complicated by a ruptured infectious internal carotid artery aneurysm, which required emergency endovascular embolization. Despite the catastrophic subarachnoid hemorrhage, the patient survived with intensive multidisciplinary treatment. This case highlights the diagnostic pitfalls of invasive fungal sinusitis and the catastrophic risks of empirical corticosteroid administration for suspected inflammatory diseases without excluding a fungal etiology.