NEOPLASTIC DISEASES IX CHICKENS 21 



Table 13. — Summary of Data on Nineteen Cases of Fowl Leukosis. 

 Figures in parentheses indicate number in group. 



.\ge at Necropsy Weight of Organs Expressed 



(Weeks) as Percent of Body Weight 



Died Killed Liver Spleen Kidney 



(10) (9) (12) (12) (8) 



Maximum 114 99 9.12 1.87 1.18 



Minimum 16 24 3.75 .39 .54 



Average 47.7 47.5 6.71 .99 .76 



A fibrosarcoma of the musculature in the region of the scapula was found in 

 one case of erythroblastic leukosis. The tumor measured appro.Kimately 3X 

 3.5 X 2 cm. and was infiltrative in character. It represents an interesting finding 

 because of the potentiality of some strains of the leukosis agent to induce fibro- 

 sarcoma (21). Lymphocytoma of the kidney and proventriculus was associated 

 with one case of erythroblastic leukosis. In one case of leukosis, a slight en- 

 largement of the posterior portion of the nerve of Remak was noted, which proved 

 to be due to an infiltration of erythroblastic cells. This may have been caused by 

 escape of leukotic cells from the blood and their local proliferation in the tissue. 

 Hermorrhage had occurred in six cases. In four of these, capillar}- hemorrhage 

 was found in either the intestinal mucosa or subcutaneous tissue; and in the 

 other two, hemorrhage came from rupture of the liver and spleen capsule re- 

 spectively. 



Both cases of granuloblastic leukosis were associated with myelocytoma. In 

 one, foci of myelocytoma were found in the liver, kidneys, ovary, bone marrow, 

 thymus, pancreas, and under the parietal peritoneum of the sternum. In the 

 other, the myelocytoma was not so widespread, involving only the liver, kidneys, 

 ovary, and bone marrow. The diagnosis of leukosis in both of these cases may be 

 open to question. The pathology of the marrow may be regarded as the most 

 significant feature in support of the diagnosis of leukosis. Both erythropoiesis 

 and granulopoiesis were stimulated far beyond normal limits and the foci of 

 myelocytoma found upon histological examination were confined to localized 

 areas. 



Encroachment of the marrow by infiltration of any tumor tissue will affect the 

 normal function of bone marrow but this does not lead to leukosis as indicated 

 by the findings in cases of hmphocytoma or other cases of myelocytoma, where 

 replacement of myeloid tissue may cause an aplastic anemia or leukopenia. In 

 some instances immature blood cells may enter the circulation because of a mech- 

 anical disturbance b\- the tumor in the marrow. 



Fibroma 



The diagnosis of fibroma was made on five tumors in the collection. In these 

 cases the type cell of the tumor was a neoplastic fibroblast more mature in char- 

 acter than that observed in fibrosarcoma. A brief description of the five cases 

 follows. 



1. T 40. A 4-week-old male chicken was found dead with a growth in the 

 subcutis immediately below the left eye. The tumor mass measured 4 X 2 X 1.5 

 cm. and weighed 13 grams. There was no evidence of metastasis and the cause 

 of death was not determined. 



