Schwannomat

Schwannomat, or schwannomas, are benign tumors arising from Schwann cells that form the myelin sheath of peripheral nerves. Most schwannomas are solitary and slow-growing; multiple lesions may occur in schwannomatosis. They are usually well circumscribed and encapsulated, and they grow along a nerve while often displacing it rather than invading it. Malignant transformation is rare.

Common locations include the head and neck, spinal nerve roots, and, in the cranial region, the vestibular nerve, leading to vestibular schwannoma (acoustic neuroma). Symptoms depend on location and may include a painless mass, numbness or tingling, pain, weakness, or, for intracranial tumors, hearing loss, tinnitus, balance problems, or facial nerve palsy.

Diagnosis relies on imaging and, if needed, tissue diagnosis. MRI with gadolinium is the preferred modality and typically shows a well-defined, enhancing mass along a nerve. CT can help for skull-base assessment. Histology shows Antoni A and Antoni B patterns with Verocay bodies; tumor cells stain S-100 positive.

Treatment ranges from active surveillance for small, asymptomatic tumors to surgical excision with nerve-sparing techniques. Radiotherapy, including stereotactic radiosurgery, is an option for unresectable or residual lesions. Prognosis is generally favorable, but recurrence can occur after incomplete resection. In familial contexts, schwannomas may be part of neurofibromatosis type 2 or schwannomatosis, which have distinct genetic bases (NF2 gene in NF2; SMARCB1/LZTR1 in schwannomatosis).