schwannoma

Meaning of schwannoma: A schwannoma is a nerve sheath tumor that is nearly always benign, most often affecting a peripheral nerve or the nerve supplying hearing and balance.

Definition of schwannoma

A schwannoma is a tumor that arises from Schwann cells, the cells that form the protective, insulating sheath surrounding nerve fibers in the peripheral nervous system. Schwannomas grow slowly and are almost always benign, meaning noncancerous, though rare malignant forms have been described.

A schwannoma can develop along nearly any peripheral nerve, and when it arises on the nerve responsible for hearing and balance, it is specifically called a vestibular schwannoma, sometimes referred to by the older term acoustic neuroma, even though it originates from Schwann cells rather than from nerve cells themselves. As a schwannoma enlarges, it can compress the nerve it surrounds or nearby structures, producing symptoms related to that nerve's function, such as numbness, weakness, or, for a vestibular schwannoma, hearing loss and balance problems.

Because a schwannoma grows from tissue surrounding the nerve rather than from the nerve fibers themselves, careful surgical removal can often preserve the underlying nerve's function, depending on the tumor's size and location.