54 MASS. EXPERIMENT STATION BULLETIN 391 



Although it is not to be inferred that the identification of tumors from mac- 

 roscopic examination only is a recommended procedure, it must be recognized 

 that routine histological examination may not be practical in laboratories estab- 

 lished only for the examination of poultry specimens. Even though there may be 

 considerable error in such tentative diagnoses, the laboratory records would, 

 however, be more understandable and usable if such identification were available. 



Perhaps the accurate diagnosis of the less common neoplasms is not of economic 

 importance since they are observed only infrequently. At the present time, 

 heredity in relation to neoplastic disease is receiving much emphasis. Many 

 flock owners are selecting families for their breeding flocks on the basis of tumor 

 incidence. If heredity is of importance in certain types of tumors and not in 

 others, there ma\' be unnecessary- elimination of families unless the types of 

 tumors are identified. 



Concomitant Tumors 



Two different types of neoplasia were found in the same chicken in nineteen 

 instances. These ha,ve been mentioned in the sections dealing with the various 

 types of neoplasia, and only a brief comment will be made here to summarize 

 the findings. 



Lymphocytoma was found to exist with embryonal nephroma in four cases, 

 with neurogenic sarcoma in one case, and with leutosis in one case. Leukosis was 

 associated twice with myelocytoma and once with fibrosarcoma. Myelocytoma 

 and embryonal nephroma were both found in one bird. Both histiocytic sarcoma 

 and hemangioma occurred in one chicken. The diagnosis of both leiomyoma and 

 carcinosarcoma was made in four cases, and leiomyoma of the oviduct was 

 found with epithelioblastoma of the ovary twice. Adenoma of the thyroid and 

 melanoma of the tongue were coexisting tumors in one case, and in another case 

 an adenoHTa of the pancreas was found in a bird which also had a large fibro- 

 sarcoma in its pelvic cavity. 



Such concomitant neoplasia excites interest in the possibility of an etiological 

 relationship. Only two combinations of concomitant neoplasia were found in a 

 sufficient number of cases to attract attention. The explanation of the com- 

 bination of lymphocytoma. and embryonal nephroma, found four times, on an 

 etiological basis does not seem logical. Embryonal nephroma is usualK- regarded 

 as a neoplasm which results from a derangement of tissue during embryonic life; 

 whereas the hypothetical agent (if such exists) of lymphocytoma may be as- 

 sumed to exert its action in post-embryonic life. Thus the two diseases seem to be 

 initiated at different periods of life and it appears unlikely that an etiological 

 relationship exists. 



The association of leiomyoma with tumors of epithelial origin, especially car- 

 cinosarcoma, is discussed in the section dealing with carcinosarcoma. Both 

 epithelioblastoma and leiomyoma were more common in birds of the older age 

 group and this would tend to increase the possibility of both occurring in the 

 same chicken. The number of cases in the study is small and for the present 

 the association of leiomyoma and epithelioblastoma should probably be re- 

 garded as merely incidental. 



