Schwannomas arise from the myelin-producing Schwann cells that surround the nerve and often occur in adults between 20 and 50 years of age. Frequent sites of involvement include the head and neck or flexor surfaces of the extremities [1]. Although benign, these tumors can cause clinical concern when they arise in the deep portions in the extremities, retroperitoneum, or posterior mediastinum [2]. Although schwannomas can be suspected on radiologic examination, needle core biopsies are often performed to exclude other malignant neoplasms, such as malignant peripheral nerve sheath tumor.

Schwannomas can vary in appearance. A cellular schwannoma is predominantly composed of dense Antoni A areas. A schwannoma with degenerative changes (ancient schwannoma) can show perivascular hyalinization (Fig. 9.4) or cells with degenerative atypia (Fig. 9.5).

Neurofibroma is a benign nerve tumor that frequently arises in the skin as a painless circumscribed nodule. It can also manifest as a large mass in association with larger nerves in deeper sites such as the abdomen [6]. Multiple and large neurofibromas occur in patients with neurofibromatosis type 1 (NF1 ) or neurofibromatosis type 2 (NF2 ). Additional findings of NF1 include café-au-lait spots of the skin , Lisch nodules , and optic gliomas . Additional features of NF2 include bilateral vestibular schwannomas , meningiomas, and gliomas [7].