PSEUDOLEUKEMIA 93 



tissue throughout the body and often marked enlargement of the 

 spleen. Foci of lymphoid cells or lymphoid infiltration are 

 found in the liver, less often in the kidneys, lungs, digestive tract, 

 bones and other organs The histological structure of these is 

 essentially the same as in lymphatic leukemia except that the blood 

 vessels are not crowded with lymphocytes. 



Cases have been observed in horses, dogs, swine, calves, cattle, 

 cats and in domestic fowls. Data as to the frequency of the occur- 

 rence of cases is not at hand. Friedberger and Frohner state that 

 according to their experience it is by no means rare in dogs and 

 it has sometimes been seen in horses. There is a good deal of con- 

 fusion as to the diagnosis. Hyperplasias of the lymph glands or 

 spleen clue to other causes, as tuberculosis or glanders or malignant 

 tumors (lympho-sarcoma) affecting lymph glands, may have been 

 mistaken for this disease, while many cases may have escaped 

 diagnosis. 



Relation of pseudoleukemia to leukemia and sarcoma. The 

 histological changes in lymphatic leukemia and in pseudoleukemia 

 are very similar. Many investigators consider them different 

 stages of the same disease. Cases of pseudoleukemia are recorded 

 in which there has been a marked increase of lymphocytes shortly 

 before death (Paltauf, Pappenheim and others). On the other 

 hand the great majority of cases of pseudoleukemia run a chronic 

 course showing no tendency to change to leukemia. 



Lympho-sarcoma and pseudoleukemia are distinguished by 

 lympho-sarcoma having a tendency to infiltrative growth and the 

 formation of true metastasis. In lympho-sarcoma the lymph 

 glands have lost their characteristic structure and are composed 

 of a diffuse growth of lymphoid cells of varying size and often also 

 of giant cells. Transitional forms between chronic pseudoleukemia 

 and the rapidly growing infiltrating lympho-sarcoma with true 

 metastases have been reported. 



The liver is the organ best adapted to distinguish by histological 

 examination, leukemia and pseudoleukemia from generalized 

 lympho-sarcoma. The characteristic collections of cells found in 

 pseudoleukemia and leukemia do not occur in sarcoma. The 

 abundant blood vessels of the liver render it easy to distinguish 

 between leukemia and pseudoleukemia. 



