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Table 20. — Relative INCIDE^"CE of Neoplasms in Collections A, B, and C
Correlated with Source.



Type of
Neoplasia



A and B Combined C



Entire Series



Number Percent Number Percent Number Percent Number Number Percent
of of Birds of of Birds of of Birds of of of Total

Cases Examined Cases Examined Cases Examined Cases Cases Neoplasms
(1781) (523) (2304) Found

(384)



Lymphocytoma 112 6.29

Leiomyoma.... 11 .62
Embryonal

nephroma. . . 13 .73

Myelocytoma . . 14 .78

Leukosis 14 .78

Epithelio-

blastoma. ... 10 .56

Fibrosarcoma. . 12 .67

Carcinosarcoma 2 .11
Neurogenic

sarcoma. .... 3 .17

Hemangioma... 4 .22

Fibroma 3 .17

Cholangioma. . . 3 .17

Hepatoma 2 .11

Histiocytic

sarcoma 3 .17

Myxoma 2 .11

Thymoma 2 .11

Rhabdomyoma 2 .11
Osteochondro-
sarcoma 1 .055

Fibrochondro-

sarcoma

Melanoma 1 .055

Lymphangioma 1 .055

Mesothelioma.. 1 .055

Teratoma

Total 216 12.1



36


6. 89


148


6.41


65


213


55.5


21


4.02


32


1.39


2


34


8.9


1


.19


14


61


7


21


5.5


3


.57


17


.74


3


20


5.2


3


.57


17


.74


2


19


4.9


7


1.34


17


.74





17


4.4


2


.38


14


.61


2


16


4.1


5


.96


7


.30





7


1.9







3


.13


2


5


1.3







4


.17


1


5


1.3


1


.19


4


.17


1


5


1.3







3


.13


1


4


1.0







2


.09


1


3


.79







3


.13





3


.79







2


.09





2


.52







2


.09





2


.52







2


.09





2


.52







1


.04





1


.26


1


.19




.04







.26









.04







.26









.04







.26









.04







.26


1


.19




.04







.26



The relative incidence of the different varieties of neoplasia is indicated in
Table 20. In addition to the numbers of different types of neoplasia found in
collections A, B, and C, the frequency of incidence is calculated according to the
source of material. Since collection C was derived from miscellaneous sources,
data on relative frequency were not available. In order to provide a larger sample
from which to obtain information on incidence as related to breed, sex, age, and
season, the data for collections A and B were pooled. The distribution of all
chickens over six weeks of age examined in the material providing collections
A and B is given in Table 21, with respect to breed, age, and season of necropsy.
Comparable data on the neoplastic diseases f round in collections A and B are
given in Table 22.

Only a few varieties of neoplasia are represented in sufficient numbers to justify
an attempt at judging their rate of incidence in birds examined for disease. These
are lymphocytoma, embryonal nephroma, myelocytoma, leukosis, and fibro-



44



MASS. EXPERIMENT STATION BULLETIN 39i



sarcoma. The rate of incidence of these tumors was essentially similar in col-
lections A and B. Leiomyoma, epithelioblastoma, and carcinosarcoma seemed
to be relatively more common in chickens from the source of collection B and
may be regarded as types of neoplasia associated with advanced age (the average
ages of birds in which such tumors were found were 66.5, 67.1, and 114.1 weeks,
respectively, Table 22). The greater incidence of these tumors in collection B is
probably due to the different proportion of old birds examined. More than twice
as many birds over 12 months of age were examined from the source of collection
B (237 birds) as from the source of collection A (1 10 birds). Embryonal nephroma
appeared to be more common in birds of collection A, but the addition of one or
two more cases to collection B would have raised the incidence rate to a level
comparable with that of collection A.

Therefore, collections A and B were essentialK' similar with respect to the
incidence of the commoner forms of neoplasia.

In considering all forms of neoplasia, lymphocytoma was the most common
(55.5 percent of 384 tumors studied). Although none of the other types of neo-
plasia were of striking frequency, six other varieties (leiomyoma, embryonal
nephroma, myelocytoma, leukosis, epithelioblastoma, and fibrosarcoma) ac-
counted for 3i percent of the tumors.



Table 21. — Distribution of Chickens over Six Weeks of Age Examined

FOR Disease. Arranged x-Xccording to Age, Breed, Sex, and Quarter of

Year When Necropsied.

Collections A and B of Neoplasms were obtained from these birds.







Distribution by Breed


,




Distributi


on


Distribution by




















by Sex




Quarter of Year


£


•s




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o

05




o

o
Pi
s:

a
o
















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C

o

2






o






0)








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D

•a
o


12 3 4




W


^







c






3 3










a

3
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o

11

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6

•z

"ca
o
H


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a!

03


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U


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IS
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11

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5
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.2 2


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V


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c

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11




2— 3


555


285


86


103


9


9


4


59


137


102


316


94* 226 161 74*


4— 6


409


272


41


49


16


10


6


15


323


54


32


14* S3* 247 95


7— 9


567


413


70


47


13


7


15


2


509


44


14


103 8* 109* 347


10—12


426


303


38


19


16


14


3


3i


324


72


30


247 103 25* 51*


13—15


145


127


10


7




4




2


120


17


8


2* 93 50


16—18


79


65


5


4


3


->






74


5





58 21


19—21


46


43




1


2








33


13





14 32


22—24


34


32








2






26


7


1


20 13 1*


254-


43


40


1


1








1


29


14





7 15 12 9


Total


2304


1580


251


226


59


48


28


112


1575


328


401


501 511 662 630



*No chickens from Collection B are represented in these groups.

Breed

Neoplasia was found in only three breeds to an extent sufficient to warrant
detailed study of the data. The difficulty of dealing with small figures again
presents itself. A preliminary examination of the data in Tables 21 and 22 in-
dicated that comparisons should be made of the incidence of lymphocytoma,
myelocytoma, fibrosarcoma, and leukosis. The comparison was drawn and the



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Online LibraryMassachusetts Agricultural Experiment StationBulletin - Massachusetts Agricultural Experiment Station (Volume no.379-398) → online text (page 55 of 77)