A 36-year-old man consulted because of a 5-year history of a slowly growing mass in the left upper arm. At first he thought that it was a lymph node (“kulani”) but it continued to grow, and was accompanied by a tingling sensation in the little finger, especially when he accidentally hits the mass. 

He consulted a local surgeon, who ordered an MRI that showed that it was a nerve sheath tumor. The local surgeon said that he would have to cut the nerve along with the tumor, and that he would harvest a nerve graft from the leg and use it to repair the cut nerve. This would result in the patient being unable to use his hand or move his fingers after the surgery. The patient was scared and did not undergo surgery. However, the mass continued to grow in size, prompting a second opinion with another surgeon. 

On examination, there was a round mass in the left upper arm, about the size of a pingpong ball. There was also occasional numbness and tingling in the little finger. 

The patient underwent surgery to remove the tumor. The tumor was arising from the ulnar nerve, one of the nerves responsible for hand and finger movements. The surgeon was able to separate the tumor from the nerve and remove it completely. The patient did not have any weakness or new numbness after the surgery. He was especially happy because the tumor was removed without any complications and he did not need to have his nerve cut and undergo graft repair.