An Atypical Case of Chronic Fungal Rhinosinusitis: Temporary Symptom Relief Resulted in a Delay of Diagnosis and Brain Abscess.

A 67-year-old diabetic man with chronic invasive fungal rhinosinusitis (IFRS) experienced mild, remitting visual symptoms, delaying diagnosis. Despite early MRI evidence of orbital apex inflammation, spontaneous symptom resolution led to discontinuation of hospital visit. Eleven months later, he developed orbital apex syndrome and intracranial complications. Emergency surgery and antifungal therapy were initiated, but vision loss persisted. This case underscores the risk of transient symptom remission masking IFRS progression, emphasizing the importance of early intervention.