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Epidermoid and Dermoid Cysts

Last Updated: September 30, 2018

Resection of a Multicompartment Cerebellopontine Angle/Petroclival Epidermoid Tumor via the Retrosigmoid Transtentorial Approach

Epidermoid and dermoid tumors are actually not neoplasms, but rather ectoderm-lined inclusion cysts. These lesions are thought to arise during neural development when surface ectoderm does not entirely separate from the neural tube between the third and fifth weeks of embryonic development. They can also be iatrogenic after lumbar puncture or traumatic following stab injuries.

Epidermoids are composed strictly of squamous epithelium, whereas dermoids contain elements of all layers of skin, including squamous epithelium, hair, sebaceous glands, and fat. Dermoids and epidermoids account for about 1% of all intracranial tumors, are very slow growing, and have been associated with craniovertebral junction anomalies and Klippel-Feil syndrome.

Malignant transformation into squamous cell carcinoma is possible, but very rare. Epidermoids are most commonly found in the cerebellopontine (CP) angle and are the third most common tumor in that location after vestibular schwannomas and meningiomas. They also occur...