Epidermoid cyst of the anterior clinoid process: report of a unique finding and literature review of the middle cranial fossa locations

Abstract Background Epidermoids cysts are relatively rare, benign, congenital tumours, representing from 0.3% to 1.8% of all intracranial lesions. When extradural, they are most commonly reported in the temporal or parietal bones as intradiploic lesions; when intradural their most common location is the cerebellopontine angle and less frequently the middle cranial fossa. Herein we present a unique case of an extradural-intraosseous epidermoid cyst of the anterior clinoid process, integrating our single-case experience into a focused literature review of these lesions, when located in the middle cranial fossa. Case description A 49 years old man came to our attention with history of head trauma. Urgent brain CT and elective brain MRI showed imaging suggestive for an anterior clinoid process epidermoid cyst. Through a pterional approach, the lesion was completely removed with microsurgical endoscope assisted technique. MRI at one year follow up showed no recurrence. Methods Current literature on epidermoid cysts located in middle cranial fossa was reviewed. A total of 22 papers, containing 70 epidermoid cyst were selected for the review. Symptoms at presentation; anatomic location; surgical approach; extent of resection and recurrence; outcome after surgery and at follow up were analysed for each case. Conclusions In the 70 published cases of middle fossa epidermoid cysts, the majority presented with trigeminal neuralgia. Most of the cases were operated through a pterional approach, while recent literature showed an increasing interest in endonasal endoscopic techniques. Subtotal resection is not a straight predictive value for recurrence; post-operative neurological deficits incidence is low and generally resolve at follow-up.