Schlumberger and Lucki — Tumors in Fishes 



671 



was found on the back of 4 goldfish Carassius awatus 

 near iu head. Tho«i^ no scales i*ere present in the 

 overiying skin, ulcastioo was absent. Histologically 

 the lesion was composed prinutrily of qiindle-shaped 

 ceUs. Attempts to transplant the tumor to other gold- 

 fish were unsuccessful. 



Taxahashi, 1929: Embedded in the trunk muscles 

 of a coalfish Tkeragra chakogrttmma was a gray-white 

 tumor, 4 X 3.5 z 3.2 cm. The overlying skin was intact. 

 The tumor parenchyma consisted of ^indle and round 

 cells; there was no evidence of infiltration. Bits of the 

 neoplasm were inoculated into IS crucian carp; in none 

 was there any growth. 



Taxahashi, 1929: A cherry-sited, firm uniformly 

 white tumor was found in the body wall near the caudal 

 fin of a rockfish Sebastodes mermis. Histologically it 

 consisted of bands and whoris of connective tissue. 



Thomas, 1933 a: A pedunculated fibroma 9 z 7.5 

 cm. was found attached to the mucosa of the intestine, 

 near the pylorus. The host was a 9 year old codfish. 



Smith, Coates and Strong, 1936: A small tropical 

 aquarium fish Rasbora damcomus bore a sharply cir- 

 ctmiscribed, encapsulated, black tumor in the region 

 of the dorsal fin. It consisted of loosely arranged inter- 

 lacing bundles of elongated connective tissue cells. 



Kkevbebg, 1937: In a brown trout Salmo trutta a 

 slightly lobulated, firm, pink tumor was discovered 

 in the abdominal cavity. The mass measured 18 cm. 

 in diameter, and was attached to the serosa of the in- 

 testine by a narrow pedicle. The parenchyma was com- 

 posed of fibrous tissue, some of which was necrotic. 

 No mitoses were present. 



SARCOMA (UNCLASSIFIED) 



The intermutability of mesenchymal tissues, and 

 the complexity of timiors arising from these tissues, 

 render their classification difficult (195a, 231a). 

 Moreover, the boundary between non-malignant and 

 malignant mesenchymal tumors is frequently vaguer 

 than in epithelial tumors. Hence it is quite p>ossible 

 that some timiors here listed as sarcomas actually 

 belong among the fibromas. It seems best therefore 

 to list these two groups in proximity. No attempt 

 has here been made to subdivide the sarcomatous 

 timers, other than separating the osteosarcomas and 

 lymphosarcomas. 



The sarcomas form the largest group of piscine 

 neoplasms, having been observed in 31 spedes 

 (Table 8). The predilection of the connective tis- 

 sues to imdergo nialignancy is not unique to fishes; 

 it also occurs in certain mammals such as the rat 

 (24). The majority of the tumors listed in Table 8 

 had their origin in the dermis or subcutaneous 

 tissues. However, this may not represent the true 

 relative organ incidence since such growths would 

 be more likely to attract attention than neoplasms 

 of the viscera. 



Of particular interest are a number of 

 that appear to arise on an environmental basis. 



Three groups of investigftton have reported in- 

 stances in which subctttaneoas sarcomas wppeMnd 

 in several goldfish Carassius auraius that had been 

 kept in the same tank. Roffo (171) observed a 

 small ulcerated tumor on the left side of a gcddfish, 

 just anterior to the dorsal fin. Hurtnlogirally the 

 neoplasm consisted <tf connective tissue arranged fai 

 bundles, among which were pleomorphic cells, some 

 of which bore two or three nuclei. Similar tunxirs 

 developed in 7 of 20 fish kept in the same aquariunu 

 After the diseased fishes were removed and the tank 

 was disinfected, no further ttmiors devdoped. Moot- 

 pellier and Dieuzeide (138) reported that a stn(^ 

 tumor was present in the body siu^ace of each of 

 five goldfish Carassius auratus that had been kept 

 in the same aquaritmi. Histologically the lesions 

 were identical, all were fibrosarcomas, the neoplastic 

 fibroblasts had elongated clear nuclei with promi- 

 nent nucleoli. Bits of one of the tiunors wore inocu- 

 lated into the caudal fins of three gddfish. After the 

 lapse of a year no tumors had devdoped. Six addi- 

 tional fish were inoculated and examined after a 

 shorter period. They likewise failed to show tumor 

 growth. 



We ourselves (123c) have lately given an account 

 of 30 tumor-bearing goldfish all but two of fdiich 

 were obtained from 3 small poob. It was found 

 characteristic of this neoplastic disease that it is 

 prevalent in certain poob and absent or rare in 

 others. Wliere prevalent, the number of tumcMr-bear- 

 ing fishes, as a rule, gradually increases. We have 

 presented evidence that the factors which induce 

 the tumors are environmental rather than heredi- 

 tary. The neoplasms arise in the corium or subcu- 

 taneous tissue and are usually solitary. Their rate 

 of growth b generally slow, althou^ some grow 

 rapidly and attain relatively large slae (Ftp. 20, 21 ). 

 The hbtological character of these growths exempli- 

 fies the difficulty of accurately classifying niesen- 

 chymal tumors. The smaller tumors resemble fibro- 

 mas or occasionally myxomas (Fig. 24), the larger 

 fibrosarcomas (Figs. 22, 23), but the paucity of 

 fiber-formation makes a purely fibroblastic origin 

 doubtful. The precise histogenesb of these neo- 

 plasms b as yet undetermined. We have tentatively 

 grouped them here with the sarcomas, although in 

 our paper we have referred to them sin^>ly as **m«h 

 enchymal tumors." It b likely, though not as yet 

 ceruin, that these tumors are similar to the goldfish 

 tumors reported in the literature as fibrosarcomas or 

 fibromas. 



