Introduction:
Isolated sphenoid sinusitis is a rare paranasal sinusitis, accounting for less than 3% of sinus infections. Fungal infections cause 10% of these cases and are often missed due to nonspecific symptoms.

Aim:
This case report highlights the importance of isolating sphenoid fungal sinusitis in patients with chronic, nonspecific headaches and emphasizes the need for early otorhinolaryngology referral.

Case study:
A 67-year-old woman with well-controlled diabetes mellitus presented with a 10-year history of severe, nonspecific headaches. After multiple treatments and normal neurological examinations, a CT scan revealed isolated left sphenoid sinus soft tissue density with calcification and erosion. Endoscopic sphenoidotomy confirmed fungal balls, leading to a diagnosis of chronic granulomatous invasive fungal sinusitis.

Results and discussion:
Isolated sphenoid fungal sinusitis predominantly affects immunocompetent individuals, particularly olIsolated sphenoid fungal sinusitis predominantly affects immunocompetent individuals, particularly older women. Diagnosis relies heavily on imaging, as nasoendoscopy may not detect abnormalities. Endoscopic trans-nasal sphenoidotomy is the preferred surgical treatment for isolated sphenoid lesions.

Conclusions:
(1) Chronic, nonspecific headaches unresponsive to conservative treatment should raise suspicion of isolated sphenoid fungal sinusitis. (2) Early otorhinolaryngology referral, proper endoscopic examination, and appropriate radiological imaging are crucial for timely diagnosis and treatment, preventing potentially severe complications.