PROLIFERATIVE DISEASES 



in the group are the leukaemias, multiple myelomatosis, 

 Hodgkin's disease and a variety of rarer conditions compre- 

 hensively referred to as reticuloses. 



2. General considerations 

 Experimental work on the theme of proliferative disease of 

 mesenchymal cells has been largely confined to mice and 

 chickens, and in both species the possibility of inducing some 

 types of proliferative lesion with virus-like agents has added 

 special interest to their investigation. 



Perhaps the best justification for examining the pathology 

 of human reticular tissue for evidence on a theme which 

 provides a formally similar mechanism for antibody pro- 

 duction and for malignancy is provided by the notorious 

 difficulty of deciding whether Hodgkin's disease and other 

 adenopathies are inflammatory or neoplastic in character. 

 In addition, most of the types of cell in which we are interested 

 are relatively mobile and have, regularly or occasionally, 

 representatives in the circulating blood where they are easily 

 available for investigation. Further, affected lymph nodes 

 tend to be widely distributed and many are superficial 

 enough to allow accurate assessment of change in size and to 

 make biopsy of a typical gland a routine clinical procedure. 

 As a starting point, we may adopt Marshall's (1956) 

 classification of hyperplastic and neoplastic conditions of the 

 lymph nodes. 



According to this there are four types of reticular tissue 

 hyperplasia : 



(i) Regenerative. 



(ii) Functional, for example, of macrophage cells in 

 reaction to foreign bodies and certain lipoid disorders, 

 and hyperplasia of all elements in response to antigenic 

 and infective agents — the typical lymph node of a 

 chronic infective process, 

 (iii) Endocrine, as in Addison's disease, 

 (iv) of unknown origin, for example, sarcoidosis. 



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