Schwannoma

A schwannoma is a type of benign tumor that develops from the Schwann cells, which are responsible for producing the protective covering (myelin sheath) around nerves. These tumors most commonly affect the peripheral nervous system, which includes nerves outside the brain and spinal cord. Schwannomas usually grow slowly and can cause symptoms by pressing on nearby nerves or tissues, leading to pain, numbness, or weakness in the affected area. They can occur anywhere in the body but are often found on nerves in the head, neck, or limbs. Although they are generally noncancerous, their location and size can impact nerve function and quality of life.

Schwannoma is a benign, encapsulated tumor arising from the Schwann cells of the peripheral nerve sheath. It is characterized by a well-demarcated mass composed of spindle cells with alternating dense (Antoni A) and loose (Antoni B) areas histologically. The tumor typically results from a loss of function mutation in the NF2 gene, leading to decreased production of the tumor suppressor protein merlin. Schwannomas most commonly present as solitary lesions but can be multiple in patients with neurofibromatosis type 2. Clinically, they cause symptoms by compressing adjacent nerves, resulting in localized pain, paresthesia, or motor deficits. They rarely undergo malignant transformation but require differentiation from other peripheral nerve sheath tumors such as neurofibromas.