Epidermoid Cyst at the Root of the Sphenoidal Pterygoid Process: A Rare Case Report

Epidermoid cysts of the skull base are rare. We present the case of a woman with an epidermoid cyst at the root of the sphenoidal pterygoid process. She experienced tightness of the forehead skin without headache. Computed tomography (CT) scan revealed a hypodense lesion at the base of the skull in the right middle cranial fossa, which had partly eroded the pterygoid root. Magnetic resonance imaging (MRI) scan revealed a soft cystic mass that eroded the pterygoid root with hypo-/iso-intense on T1-weighted images, hyperintense on T2-weighted images, inhomogeneous hyperintense on diffusion-weighted images, a slightly low apparent diffusion coefficient, and no enhancement, suggesting a diagnosis of an epidermoid cyst. Surgical excision was performed using a nasal endoscope via the pterygoid process-root approach. A histopathological examination confirmed the diagnosis of an epidermoid cyst. At the 6-month follow-up, no recurrence was found on MRI or nasal endoscopy, and the symptoms of forehead tightness disappeared. In conclusion, epidermoid cysts at the root of the sphenoidal pterygoid process are exceptionally rare. Preoperative MRI and CT scans are necessary for the correct diagnosis and differentiation of other low-growing lesions. Nasal endoscopy is crucial for surgical excision and postoperative follow-up for potential recurrence.