TUMORS. 305 



as is too often done, that the multiplicity of related tissue forms in a 

 tumor point toward embryonal origin. 



Complex Congenital Growths Teratoma. 



These are tumors which frequently contain a great number of differ- 

 ent forms of tissue, such as various forms of fibrillar connective tissue, 

 cartilage, bone, teeth, hair, skin, muscle, and glands. These are most 

 frequently found at the lower end of the spine, 1 about the head and 

 neck, or in the generative organs. Some of them probably arise by an 

 inclusion of portions of another fostus, and are thus rather malformations 

 than tumors in the limited technical sense. Among these are sometimes 

 classed other and simpler congenital malformations, such as dermoid 

 cysts, congenital angiomata, and the so-called pigrnented nsevi or moles. 



Special Tumor Types. 



There are types of tumors which are not readily brought into the 

 usual general classifications, since they are formed of special kinds of 

 tissue. These have received distinctive names. Thus there are peculiar 

 tumors formed of placental tissue called deciduoma ; of tissue resembling 

 the adrenals, hyper-nephroma, etc. 



Lubarsch's Grouping of Tumors for Practical Purposes. 



Lubarsch has suggested the following grouping of tumors, for practical purposes, 

 without special reference either to their histogenetic or histological characters: 



1. Tumors which, although differing from the tissues in which they originate in the 

 arrangement of their elements, usually increase in size but slightly or temporarily. In 

 this group are the teratoid growths and those originating in embryonic displacements, 

 such as congenital nsevi, certain gland-like tumors, myoma, fibroma, liporna, chondroma, 

 and osteoma. Such tumors are usually of little practical importance. 



2. Tumors which, although conforming in general to the normal tissue type in 

 growth and structure, still reveal a considerable independence of their surroundings; 

 such are larger myomata, adenomata, angiomata, lipomata, which may grow slowly 

 and with interruptions, and may when growth ceases through degenerative processes ol 

 necrosis undergo retrogression or even disappear altogether. 



3. Tumors which seem to be largely emancipated from the usual physiological con- 

 trol of normal tissues, both in the rapidity and extent of growth and in the fixity of the 

 cell type in form and function. In this class are the tumors which are destructive and 

 invasive in their growth, especially the sarcomata and carcinomata. 



These three classes may in reality be considered to represent only stages in the 

 growth of tumors in general ; since the more destructive forms may in early stages con- 

 form to the characters of the other groups, while, on the other hand, tumors of the less 

 aggressive types may assume the autonomy and significance of the malignant forms. 

 These classes of tumors are not of course distinct, and many intermediate types may 

 occur, but this grouping seems to the writer fairly to indicate a real difference in char- 

 acter and significance in tumors as a whole which it is of practical advantage to recog- 

 nize, and which is often lost sight of in the more technical classifications. 



1 For a critical summary, with bibliography, of tumors of the sacral region, see Borst, 

 Centralbl. f. Pathologic, Bd. ix., p. 449, 1898. 

 20 



