Epidermoid 101:  Just the Basics!

The intracranial Epidermoid Brain Tumor is also referred to as epidermoid cyst


The incidence of intracranial epidermoids is between 0.2% to 1.8% of all brain tumors. They most often are found deep in the skull base, occurring typically in the Cerebellopontine Angle (CPA), which is involved in 40 to 60% of the cases diagnosed.

http://neurosurgery.stanford.edu/patient_care/brain_tumor.html  This benign (i.e. non-cancerous) tumor of the brain is  made up of normal skin cells (stratified epithelial lining) on the outside, and fatty acids and (desquamated) keratin are on the inside of the tumor or sac. Only the sticky outer layer is alive thus sticking to brain tissues and nerves.


These tumors arise from ectodermal (skin) cells entrapped during neural tube closure. They form from the 3rd to 5th week of fetal development. Rarely, it can be acquired because of injury or surgery.

Slow Growing

Intracranial epidermoid tumors are slow-growing lesions, which may recur after incomplete resection (surgery), but may do so over many years.  These slow growing benign tumors encase and surround nerves and arteries rather than displacing them and the treatment of choice is radical surgery. Up to 20% may involve or be near the ventricles. The reported recurrence rate for a subtotal removal is 30% after a mean interval period of 8.1 years.

Historically patients often do not have many symptoms or a diagnosis until the second to fourth decade of life due to pressure from growth. With recent evolving technology, these congenital brain tumors are now found in young patients and with some even before birth.

A few patients have tumors that grow unusually fast, especially after surgery. We do not know why this happens. We suggest patients monitor their tumors as their neurosurgeons or neurologists suggest. We also suggest using the same facility with each scan, if possible, as minor variations may seem to indicate falsely that your tumor may be growing, when the measurements taken may be different due to differences in the MRI machines and the software used.


Epidermoid tumors strongly adhere to the brain stem or cranial nerves, and other structures with in the brain. Often residual tumor may remain after surgery, which contributes to the risk of regrowth. The nerves that have their origin in the brain are called cranial nerves. There are 12 pairs of cranial nerves that come out of the brain stem (the size of your thumb) at the base of the skull. Some of these nerves bring information from the sense organs to the brain; other cranial nerves control muscles; other cranial nerves are connected to glands or internal organs such as the heart and lungs.
https://faculty.washington.edu/chudler/cranial.html    Symptoms will vary according to what nerves the tumor may be touching.

Symptoms Caused by an Epidermoid May Include:

Headaches – often worse in the morning or by changing positions; can be constant and become more severe or more frequent; not your typical headache

Vision problems like blurred vision, double vision, or loss of peripheral vision

Loss of sensation or movement in the arms, legs, or face

Dizziness or difficulty with balance and walking, unsteadiness, vertigo

Speech difficulties

Personality or Behavior Changes:

     Learning and Memory (particularly short-term memory): Difficulty processing, storing, and remembering information; short-term memory loss.
       Attention and Concentration: Confusion, easy distraction, difficulty multitasking and planning
      Executive Functioning/General Intellectual Abilities: Decreased reasoning ability, impaired judgment, inability to connect cause and effect 

Personality  Changes:  Anger, depression, rage, fear and other emotions may be intensified, exaggerated, or seem inappropriate;  some may experience a roller coaster of emotions and changes in how they relate to others or handle previous problems and issues

Seizures, especially in someone who hasn’t had seizures before

Hearing loss or buzzing or ringing in the ear

Swallowing  or speech  difficulty

Fatigue or sleepiness

Cranial Nerve Information

The cranial nerves are 12 pairs of nerves that can be seen on the ventral (bottom) surface of the brain. See Chart: http://faculty.washington.edu/chudler/cranial.html  

Surgical Management

Epidermoid tumors are slow growing, and you may not need surgery, or  may not need surgery at the time of diagnosis. It is slow growing, so one has time to evaluate their options with several surgeons. EBTS suggests those with tumors consult several neurosurgeons with much experience in the skull base (if that is where your tumor is), and much experience with the epidermoid, as it is very unique and difficult to remove, as it is very sticky. Neurosurgeons specialize, much like Orthopedic surgeons (a hand surgeon does not operate on knees),  a general neurosurgeon may not be very experienced in the skull base,  or with the rare epidermoid, as this is a relatively new specialty. A skull based surgical center is a good place to begin a search for a qualified surgeon.

Historical Knowledge of Epidermoid/Cholesteatoma Research

The epidermoid was once also called a cholesteatoma, and is still called this in a few parts of the world. By searching both the terms epidermoid and cholesteatoma, much information is available. Today the term cholesteatoma is most often used to describe the middle ear cholesteatoma.  The use of the term cholesteatoma for the epidermoid brain tumor was termed by Cruveilhier (1829 France) in his work  and now the term cholesteatoma is used primarily for the middle ear tumor.


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