308 TUMORS. 



Technique of Fixation and Hardening. 



In general, tumors, like all tissues for microscopical study, should be cut into small 

 pieces before immersing them in the preservative fluids, and the sooner they can be 

 placed in these after removal the better will be the preservation. In some cases much 

 may be learned from large sections of tumors together with their surrounding tissues. 

 In this case the suitable portion of the tumor must be preserved whole, and is best har- 

 dened in strong alcohol. 



It is often important in the study of tumors to examine not only the fully devel- 

 oped or mature tumor structures, but also those portions in which the new growth is 

 forming and in which it is encroaching on adjacent parts. 



So that in selecting portions of tumors for preservation and study, it is not wise to 

 snip off a small piece at random, but a careful selection should be made, liberal por- 

 tions being saved, from the centre, from the periphery, and from such surrounding 

 tissues as are available. For the ordinary routine hardening of tumors, Orth's fluid 

 followed by alcohol may be recommended. 



Special Forms of Tumors. 



FIBROMA. 



The fibromata are composed of fibrillar connective tissue, which, as 

 in the physiological type, is sometimes dense and firm, Fibroma durum. 

 and sometimes loose in texture and soft, Fibroinajawlle. They are usu- 

 ally sharply circumscribed and are frequently encapsulated, but they 

 may^be ^Iffn"* and merge Imperceptibly into the surrounding tissue. 

 They are frequently small and insignificant, but occasionally grow to an 

 enormous size. Some fibromata consist almost entirely of intercellular 

 substance, containing but fewilattenedor spindle-shaped cells (Fig. 1-45) ; 

 others contain very many variously shaped cells (Fig. 146). The cells 

 are often more abundant in one part of the tumor than in another. The 

 denser varieties usually contain but few blood- ^_ 



vessels, although they are occasionally quite 

 vascular. Many of the softer varieties are 

 very vascular. Nerves are occasionally pres- 

 eut. ' The course and arrangement of the '-:-;: 

 fibres in these tumors are usually irregular, --'/ ; " ' 

 often crossing and interlacing in a most com- j'J"~ ':'-. " 

 plex manner. The ^bromata_ are usually of ^'^^ 

 slow growth, but exceptionally they grow ^e^"* 



rapidlyT-^hey are benign tumors, but by ^ 145 ._ DENSE FIBROMA OF 

 pressure on important organs, by ulceration, ABDOMINAL WALL -FIB ROM A 

 or by changing into other varieties of tissue, DURIIM - 

 they may become of serious import. Pure ^f 

 fibromata, do- not form metastases, but they are cut lengthwise. 

 are often multiple, and when so are fre- 

 quently congenital. They may recur when not fully removed. 



It seems probable that in the multiple fibromata of the skin (Fibroma 



1 For a study of elastic and reticular tissue in tumors see Baldwin, " Vaughan Anni- 

 versary Contributions," 1903, p. 495. 



