Is Grown Piloma Tumor From Upper Arm To Ulna Nerve A Cause For Concern?

My wife had surgery yesterday to remove a piloma tumor from her upper arm. it was about 5cm x 4cm. After the incision was made the surgeon found that the tumor had "grown" out of her Ulna Nerve and was beyond his skills to separate the tumor from the nerve. A biopsy is being done but they seem confident that it is benign. He recommends we locate a neurosurgeon in the Dallas, Texas area that has the skills to conduct this delicate surgery without permanent nerve damage. I forgot what he called this situation but was told it was a fairly rare occurrence. What is this called and who should we contact?