NEOPLASTIC DISEASES IN CHICKENS 31 



1. T 143. An 8-month-oId pullet affected with chicken pox was killed for 

 examination. The liver was moderatel}' enlarged by the presence of numerous 

 areas of hemorrhage, particularh- common in the right lobe. The hemorrhages 

 were not fresh and were only partl\- organized. The largest area of hemorrhage 

 was approximately 2 cm. in diameter. In the substance of the right lobe of the 

 liver was an oval mass of firm, gray tissue measuring 9X5 mm. Histologically 

 this mass was composed of numerous irregular acini of bile duct epithelium 

 between which were arranged bundles of fibroblasts and irregular areas of myelo- 

 cytes and "polyblasts. The other necropsx' findings were essentially negative 

 except for a few shallow, chronic ulcers in the ileum. No explanation for the 

 hemorrhages in the liver could be found. Fowl leukosis was suspected but the 

 bone marrow though somewhat scant in amount was in a hyperplastic and not 

 neoplastic state. 



2. T 286. A 33-week-old pullet was found dead. In the right lobe of the 

 liver was a gray-red-brown mass rather sharply defined and somewhat firmer 

 than the adjacent hepatic tissue. The mass measured 20 X 22 X 25 mm. and 

 consisted of irregular acini and tubules of low cuboidal epithelium between which 

 were niany lymphoid cells and a few connective tissue fibers (Plate XI, Figure 3). 

 There was a rather marked degree of fatty metamorphosis in the neighboring 

 hepatic cells. 



3. Case 283. This bird died at the age of 61 days with erythroblastic leukosis 

 induced by inoculation with material of a transmissible strain of the disease. 

 A small gray nodule of tumor tissue was found in the substance of the right 

 liver lobe. The tumor was composed of epithelial cells, which for the most part 

 were without definite arrangement, although in some areas irregular acini were 

 formed. 



4. T 242. A 12-month-old pullet with fowl pox was killed for examination. 

 The pox lesions involved a rather extensive area over the abdomen and sternum. 

 Pathology of the visceral organs was limited to the liver in which were several 

 irregular areas of gray tissue scattered in both lobes. Only one mass in the 

 right lobe was apparent in the intact specimen. The others were found upon 

 cross section. The tumor masses were intimately associated with the larger 

 blood vessels. The largest mass was 10 mm. in diameter. Numerous acini and 

 irregular tubules of bile duct cells were found in the tumor. Between the epithelial 

 elements was a dense infiltration with lymphoid cells and a light, scattered in- 

 filtration with heterophils. A rather marked fatty metamorphosis of the liver 

 cells was found. 



Cholangiomas in these cases were either single or nmlliple. All were found In 

 female chickens but the number is so small that this fact has little significance. 

 The ages of the birds at the time of examination ranged from two months to a 

 year. From the data, it would seem that cholangiomas are benign neoplasms. 

 Although the cholangioma found in Case 4 must be considered an incidental 

 finding, its multiple nature suggests that with more time for development it 

 might have been a primary cause of death. 



Thymoma 



Two cases of tumor were diagnosed as thymoma. There was a distinct sim- 

 ilarity of the macroscopic and microscopic features in both cases. 



1. T 19. A 9-month-old pullet was found dead with a marked swelling of 

 the throat in the region of the crop. Upon necropsy the swelling was found to be 

 due to an irregular tumor mass at the base of the neck on the left side. The 

 mass measured approximately 8X5X3 cm. and was relatively firm and grayish 

 pink in color. The tumor lay in the left jugular furrow, infiltrated the adjacent 

 soft structures, and closely enveloped both the trachea and esophagus. In 

 general the tumor seemed to grow upward in the neck although there was a small 

 projection beginning to enter the thoracic aperture. Deposits of urate crystals 

 were found in the pericardial sac, and both kidneys were slightly swollen and pale 

 in color, suggesting that death may have been due to a kidney insutificiency rather 

 than to the tumor. Other visceral organs were essentially normal. Microscopic 

 study indicated that the principal components of the tumor were polymorphous 

 cells larger than the thymic lymphocytes seen in a normal thymus. These cells 



