Description

• Epidermoid tumors are benign, congenital cysts that occur intradurally and extradurally. They are slow-growing and produce symptoms gradually.
• Also called epidermoid cysts, primary cholesteatomas, and epidermoid inclusion cysts
• Third most common tumors of the cerebellopontine angle (CPA)

Epidemiology

Prevalence
Rare intracranial growths constituting 1.8–2.2% of all intracranial tumors

• Presentation can be at any age but most commonly between the 3rd and 5th decades of life.
• Equal incidence in men and women
• There is a wide ethnic distribution, and there is no known preponderance in any region.

Etiology and Pathophysiology

• Considered a benign lesion; malignant transformation is rare.
• Growth is secondary to accumulation of desquamated epithelial cells; follows a linear growth rate
• Symptoms are due to mass effect and displacement of local structures. Depending on tumor location, it may result in cranial nerve, blood vessel, and brainstem compression.
• Derived from squamous epithelium that is included during neural tube closure
• Epidermoid tumors grow slowly from the buildup of keratin and cholesterol from the continual shedding of the epithelium lining the cyst.
• Formed at the time of neural tube closure between the 3rd and 5th weeks of embryonic life
• Common locations include CPA, parapontine, parapituitary, middle cranial fossa, and dipole of the fontanel.
• Multiple lumbar punctures have been known to be a rare cause.