Skull Base Erosion by Sphenoid Fungus Balls: Diagnosis and Endoscopic Treatment

Abstract

Background Fungus balls typically are innocuous lesions found in immunocompetent hosts. They are located most commonly in the maxillary sinus but may be life-threatening when found in the sphenoid sinus. Methods We review our series of four sphenoid fungus balls with skull base erosion. Results Our average patient age was 68.7 years old (56–86 years) with three women and one man. One patient was insulin-dependent diabetic, the other three patients were otherwise healthy. The most common presenting symptoms were headache and dizziness with relatively few sinus-specific complaints. Endoscopy revealed polyps in two of the four patients. Computerized tomography scans revealed thickened osteitic bone in three cases and two of the four computed tomography scans showed microcalcification. All patients had bony erosion over the internal carotid arteries. Additionally, one patient internal carotid artery thrombosis, one patient had erosion of the planum sphenoidale, and a third patient had erosion to the brainstem inferior to the sella turcica. Three patients had magnetic resonance imaging that revealed heterogeneous lesions. Two magnetic resonance images showed hypointense T1 and T2 imaging. The third was isointense on T1 and hypointense on T2. All patients were treated with endoscopic marsupialization and removal of all gross fungal debris without complications. All pathological specimens were diagnostic for fungus balls. One of four cultures was positive for fungus. All patients are asymptomatic at time of last follow-up. Conclusions Sphenoid fungus balls present with vague, non-rhinological symptoms, but may have significant local expansion and destruction. These potentially lethal lesions usually can be suspected on preoperative imaging and are best treated with endoscopic removal.