Łagodny nerwiak osłonkowy

A rare benign peripheral nerve sheath tumor characterized by a usually encapsulated space-occupying lesion composed of differentiated neoplastic Schwann cells. It most commonly arises from peripheral nerves in the head and neck region and extensor aspects of the extremities, but also from spinal and cranial nerves, especially the vestibular nerve. The tumor may be asymptomatic or cause symptoms related to a mass effect. It grows slowly and only rarely undergoes malignant transformation.