Mucocele-like lesions of the sphenoid sinus with hypointense foci on T2-weighted magnetic resonance imaging.

Lesions limited to the sphenoid sinus are relatively rare, and are obscure with respect to symptoms and physical findings. The differential diagnosis of isolated sphenoid sinus disease includes bacterial sinusitis, fungal infection, granulomatous inflammation, mucocele, and tumors. Magnetic resonance imaging (MRI) can provide information that closely reflects the composition of the tissues, sometimes permitting differentiation between pathologically distinct lesions showing similar density by computed tomography. We describe two cases involving mucocele-like lesions of the sphenoid sinus where preoperative MRI revealed a focus of hypointensity within the lesions. In both patients the sphenoid sinus was opened by a transnasal endoscopic approach, and diseased tissue corresponding to the hypointense area was removed under direct endoscopic vision. Histopathological diagnosis revealed colonies of Aspergillus in one case and necrotic granulation tissue without fungus in the other. We concluded that MRI is a crucial part of preoperative evaluation and that the transnasal endoscopic approach represents a safe and effective method for treating nonmalignant isolated sphenoid sinus disease.