Schwannoma

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	Schwannoma;
ICD-O:	9560/0
DiseasesDB	33713
MeSH	D009442

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: Acoustic neuroma, acoustic neurinoma, or acoustic neurilemoma, neurilemmoma, neurinoma, neurolemmoma, Schwann cell tumor

Overview

A schwannoma is a kind of tumor originating from the Schwann cells. The insulating myelin sheath which covers peripheral nerves is produced by the Schwann cells. Hence, one kind of tumor originating from the Schwann cells is called a schwannoma.

Schwannomas are very homogenous tumors consisting only of Schwann cells. The tumor cells always stay on the outside of the nerve, but the tumor itself may either push the nerve aside and/or up against a bony structure (thereby possibly causing damage). Schwannomas are relatively slow growing. For reasons not yet understood, schwannomas are mostly benign and less than 1% become malignant degenerating into a form of cancer known as neurofibrosarcoma.

Schwannomas can arise from a genetic disorder called neurofibromatosis. They are universally S-100 positive.

Schwannomas can arise from a genetic disorder called schwannomatosis.

Pathophysiology

Microscopic Pathology

Diagnosis

History & Symptoms

Unilateral/asymmetric hearing loss and/or tinnitus and loss of balance/dizziness are early signs of a vestibular schwannoma. Unfortunately, early detection of the tumor is sometimes difficult because the symptoms may be subtle and may not appear in the beginning stages of growth. Also, hearing loss, dizziness, and tinnitus are common symptoms of many middle and inner ear problems (the important point here is that unilateral or asymmetric symptoms are the worrisome ones).

Other Diagnostic Studies

Audiogram

Once the symptoms appear, a thorough ear examination and hearing test (audiogram) are essential for proper diagnosis.

Imaging Studies

Computerized tomography (CT) scans, enhanced with intravenous dye (contrast), and magnetic resonance imaging (MRI) are critical in the early detection of a vestibular schwannoma and are helpful in determining the location and size of a tumor and in planning its microsurgical removal.

Treatment

Schwannomas can be removed surgically, but they can then recur.