Invasive sphenoid sinus aspergillosis with normal findings on initial diagnostic tests that mimics Tolosa-Hunt syndrome-a diagnostic dilemma: a case report.

Invasive sphenoid sinus aspergillosis can mimic Tolosa-Hunt syndrome (THS), leading to frequent misdiagnoses and potentially fatal consequences. We report a case of invasive sphenoid sinus aspergillosis initially misdiagnosed as THS. A 79-year-old man presented with right periorbital pain, ophthalmoplegia, and loss of vision. Initial evaluations including magnetic resonance imaging (MRI), were normal. He was first diagnosed with THS based on clinical features. The disease progressed despite high-dose intravenous steroid treatment, and an enhancing mass-like lesion was found in the right orbital apex, cavernous sinus, and sphenoid sinus on follow-up MRI. Aspergillosis was eventually confirmed by sphenoid sinus biopsy. The patient developed cerebral infarction and finally died despite being treated with amphotericin B. Given that invasive sphenoid sinus aspergillosis may initially resemble THS, high suspicion and rapid histological examination are important for diagnosis.