From the cell of Schwann to schwannoma--a century's fruition.

The word "schwannoma" is pervasive throughout the neurosurgical community. However, little is known about the origin of the cell of "Schwann cell," the manifestation of the tumor's nomenclature, or the prominent physicians who studied its etiopathogenesis. Schwann was a founding father of cellular theory and one of the greatest scientists of the 19th century. He not only proposed cell theory but also discovered the "secondary" nerve cell and hypothesized its possible function in myelination. It took a century to confirm Schwann's hypothesis. In 1954, Geren, aided by the electron microscope, demonstrated that the cell of Schwann is responsible for nerve myelination. Concurrently, researchers worked to understand the etiology and pathogenesis of peripheral nerve neoplasms. Several attempts were made; Older, Virchow, and von Recklinghausen were the first pioneers who worked on the classification of these neoplasms. However, Masson first used the word "schwannoma" to describe peripheral nerve neoplasms other than neuromas. His French colleague Nageotte used the term "peripheral-glioma" to denote these tumors. These schwannomas were considered to have a malignant course. In 1932, Penfield attempted to classify peripheral nerve neoplasms into 3 categories: peripheral fibroblastoma, peripheral glioma, and neurofibroma of von Recklinghausen. He classified "Verocay's neurinoma," "Masson's schwannoma," and "cerebellopontine angle" tumors as perineural fibroblastoma. He believed that these tumors have a non-nerve cell, non-Schwann cell origin. He classified the tumors arising from the Schwann cell sheath as peripheral gliomas and articulated, "If any tumors are to be called schwannomas, these should be." The neurofibroma of von Recklinghausen was recognized as a separate entity, as described by von Recklinghausen himself. Murray and Stout proposed that schwannomas are essentially benign in nature clarifying the abstruseness of the benign or malignant nature of schwannoma.