Benign peripheral nerve tumor – Symptoms and causes – Mayo …

The most common benign peripheral nerve tumor in adults, a schwannoma can occur anywhere. It typically comes from a single bundle (fascicle) within the main nerve and displaces the rest of the nerve. Some schwannomas enlarge and assume unusual shapes within your spine or pelvis, such as dumbbell tumors.

https://www.mayoclinic.org/diseases-conditions/peripheral-nerve-tumors-benign/symptoms-causes/syc-20368680