520 TUMOES. 



whether such formations ever occur. Tumors containing nerves 

 have been observed most frequently on the spinal nerves, less 

 frequently on the sympathetic, and least frequently on the cere- 

 bral nerves. No positive proof has been given, however, that 

 the great quantities of nerves in these tumors are really newly 

 formed. If the internal perineurium of course connective tis- 

 sue only be augmented, the innumerable nerve-fibers are 

 pushed apart and may make the impression of constituting a 

 true neuroma. Giinsburg, Wedl, and others have demonstrated 

 that, in the nodular nerve-growths developed after the amputa- 

 tion of a limb, large numbers of the bundles of nerve-fibers, both 

 of the medullated and non-medullated varieties, were newly 

 formed. There are recorded cases in which one nerve produced 

 a number of tumors, which gave the formation a rosary-like 

 appearance $ in other cases, on a number of nerves in different 

 localities, tumors were found, and it is asserted that in such nod- 

 ules newly formed nerves were present in a large number (mye- 

 linic neuroma of Virchow). Some congenital tumors in the 

 sacral region have been found to contain a large number of 

 medullated nerves. Virchow observed teratoid tumors, composed 

 of nerve-tissue, resembling the gray substance of the brain. 



Of still more doubtful occurrence are the tumors composed 

 of non-medullated nerve-fibers, the amyelinic neuroma of Yir- 

 chow, who describes a case of recurrent ulcerative, and conse- 

 quently malignant, neuroma (" neuromatous diathesis")- Even 

 with our modern methods of investigation a positive proof of the 

 presence of non-medullated nerve-fibers is not easily obtained, 

 and many authors have doubted the existence of true amyelinic 

 neuromata. 



Most of the nerve tumors have proved to consist, in addition 

 to a varying number of nerve-fibers, of the myxomatous and 

 fibrous varieties of connective tissue. Instead of using the term 

 " spurious neuroma," we shall designate such tumors as myxoma 

 or fibroma growing from a nerve, or if the tumor contains a large 

 number of nerve-fibers, we may term it neuro-myxoma, or neuro- 

 fibroma. Most of the so-called " painful tubercles " of the skin 

 also belong to this class. (See Fig. 215.) 



Sometimes myeloma develops on or in a nerve, and, in 

 accordance with our terminology, such a tumor would be called 

 neuro-myeloma. The nerve-fibers, however, in the advancing 

 growth of the tumor are soon destroyed and transformed into 

 myeloma tissue. 



