NEOPLASTIC DISEASES IN CHICKENS 



11 



and the other 3 were of the combined diffuse and nodular form (4 percent of the 

 group of 75 cases of combined diffuse and nodular lymphocytoma). In 31 cases 

 of lymphocytoma, one organ only was involved with tumor. Lymphocytoma was 

 confined to the ovary in 10 cases, the peritoneum in 5 cases, the liver in 3, mus- 

 culature in 3, the spleen in 2, the kidney in 2, the lung in 2, the bursa of Fabricius 

 in 2, the skin and subcutis in 1, and the adrenal in 1. Single-organ involvement 

 with lymphocytoma was distributed among the forms of disease as follows: 

 diffuse, 24 cases; nodular, 4 cases; and diffuse and nodular, 3 cases. In 14 cases, 

 lymphocytoma was distributed in one of two combinations: liver, spleen, kidney, 

 gonad, and marrow (7 cases) ; and liver, spleen, and kidney (7 cases). The next most 

 frequent combination was liver and spleen only (5 cases). 



Table 6. — Number of Org.ans or Tissues Involved with Lymphocytoma. 



Figures represent percent of cases with the respective number of organs or 

 tissues involved. Cases are grouped twice: according to form of tumor and on the 

 basis of nerve involvement. Figures in parentheses are number of cases in group. 



♦Organs or tissues considered are those listed in Table 5, with the exception of the various nerves 

 and the blood. 



Degree of Involvement. — In over half of the cases where either the gonad, 

 skin and subcutis, musculature, or bursa of Fabricius was affected with lympho- 

 cytoma, the degree of involvement of these structures was Grade 4 (Table 7). 

 Organs less severely infiltrated were the liver, spleen, kidney, lung, peritoneum, 

 pancreas, and intestine, although in over half of the cases in which they were 

 affected the degree of involvement of these tissues was classified as either Grade 

 3 or Grade 4. The marrow, thymus, and proventriculus were not often severely 

 involved, as more than half of the cases in which they were affected were of either 

 Grade 1 or Grade 2. The 64 cases in which the adrenal was involved were dis- 

 tributed almost equally in each of the four grades. Nerve tissue when affected 

 usually had a Grade 3 involvement. The blood was considered to be affected 

 when cells similar to those of the tumor were found in the blood of the vessels. 

 This condition was different from the leukemic state found in fowl leukosis. 

 The blood when involved usuallv fell into the classification of Grade 1 or 2. 



