NEURINOMA is the designation of a peculiar tumor arising from the cells of the sheath of Schwann, specifically the primitive stages of the latter, and therefore the tumors are ectodermal in origin. They are composed partly of Schwann cells and partly of connective tissue, whereas they do not contain true neural tissue. A more detailed histologic description is given in works by Verocay1 and Korbsch2 and, more particularly, by Antoni,2a who, in a larger monograph, accounts for their origin and structure. A number of the peripheral tumors often contain an admixture of collagen connective tissue, which is often present in large quantities, for which reason the term fibroneurinoma, coined by Verocay, ought to be adopted as the proper designation of these tumor, instead of neurofibroma (von Recklinghausen), as theses tumors do not contain true neural tissue. The tumors, being partly solitary and partly multiple (as in von Recklinghausen's disease, also