What is a nerve sheath tumor? A nerve sheath tumor, also known as a Schwann cell tumor, is an isolated, perineural, slow-growing, benign tumor composed of nerve sheath cells. It can occur in peripheral nerves throughout the body, and is also common in the spinal canal. Nerve sheath tumors have the highest incidence among benign neurogenic tumors, accounting for approximately 5% of all soft tissue tumors. It can occur at all ages, with a peak incidence between the ages of 20 and 50, and the incidence is gender neutral. What are the symptoms of nerve sheath tumor? The tumors are most common in the limbs, head and neck, and trunk. They are more frequent around the large nerve trunks on the flexors of the extremities, such as the N fossa, elbow, axilla and wrist. The skin lesions are well-defined. Most of them are found in sensory nerves, but motor and autonomic nerves can also be involved, and the tumor rarely occurs in visceral nerves. Most peripheral nerve sheath tumors present as a single, mobile, isolated, painless mass, usually without significant neurologic symptoms. They can be found incidentally during physical examination. The tumor does not adhere to the skin, and when incidental to a nerve, it can mostly be pushed except for the point of contact. Since nerve sheath tumors are mostly found in sensory nerves, motor abnormalities are rare. Nerve sheath tumors are slow-growing, painless masses with an average duration of disease from several months to several years. The tumor is often oblong in shape. Due to the restriction of the nerve trunk course, it is typical for the mass to have limited longitudinal movement and greater lateral movement. It can cause radioactive soreness and numbness when compressing the nerve, and electric shock sensation along the nerve distribution area. Tumors occurring in large nerve trunks may even cause atrophy of the innervated muscle groups. Smaller tumors are more parenchymal in size, while larger tumors often have partial or complete cystic changes, and a few may have fluctuating sensation. When bleeding occurs, it may grow swollen along the envelope and can be easily misdiagnosed as a cyst or hemangioma. Nerve sheath tumors on the surface of the body are usually small in size, not exceeding 5 cm, while those occurring in the retroperitoneum can grow larger. Multiple tumors may grow in the same nerve trunk at the same time. How are nerve sheath tumors diagnosed and treated? Based on medical history, physical examination, combined with imaging, most of them can be diagnosed clearly before surgery. Sometimes the tumor has hemorrhage and cystic changes, which need to be differentiated from hemangioma, cyst, hematoma, etc. Nerve sheath tumors are treated by surgical excision. The nerve axon often forms the “envelope” of the tumor, so the tumor can be removed within the “envelope”. The nerve trunk can be seen at both ends of the tumor, but since the tumor is benign, the nerve trunk should not be cut off as much as possible. If there is a long time hard area in superficial area after surgery, it is often caused by local hematoma mechanization due to incomplete intraoperative hemostasis. What is the prognosis of nerve sheath tumor? Nerve sheath tumors are slow-growing benign tumors that rarely recur after surgical excision and rarely become malignant. If there are no obvious clinical symptoms, it can be followed up and observed.