Tumors of peripheral nerves

Tumors of peripheral nerves most commonly originate from the nerve sheath. In this chapter, they will be referred to as peripheral nerve sheath tumors (PNST). Arthur Purdy Stout (18851967) was a pioneer in the development of our current understanding of the histogenesis of these tumors. He was the first to identify the Schwann cell as the major contributor to the formation of benign as well as malignant neoplasms of the nerve sheath [106]. Benign nerve sheath tumors are subdivided into two separate morphological groups with different histopathological characteristics: schwannoma (also known as neurilemoma or neurinoma) and neurofibroma [30]. Intraneural ganglion is also considered to be a tumor of nerve origin. For a discussion on this tumor we refer to Chap. 1, Sect. 3.2.1. Malignant nerve sheath tumors are known under a confusing multitude of names including malignant schwannoma, malignant neurilemoma, nerve sheath fibrosarcoma, neurogenic sarcoma, and neurofibrosarcoma. In this chapter we will use the generic and widely accepted term malignant peripheral nerve sheath tumor (MPNST).