Schlumberger and Lucki — Tumors in Fishes 



667 



fish, and tend toward spontaneous regression in 

 older animals, may be related to the extensive involu- 

 tion which the thyroid normally undergoes when the 

 fish reaches sexual maturity — at the age of 3 or 4 

 years in trout. The involution of the thyroid is com- 

 pensated for, at least as concerns its oxygen regulat- 

 ing function, by an increase in the number of 

 erythrocytes in the circulating blood (40). 



The possible relation of low oxygen tension in 

 water to thyroid hyperplasia in fish receives support 

 from the work of Marsh and Vonwiller ( 131). These 

 investigators found enlarged thyroids in five sea bass 

 Serranus scriba and 5. cabriUa that died in the 

 aquarium of Naples. Since these fishes were kept 

 in fresh sea water, in which the content of iodine is 

 high, depletion of the latter cannot account for the 

 occurrence of the goiters, which histologically re- 

 sembled those of the Salmomdae. 



Thyroid enlargements have been seldom observed 

 in marine fishes hence their appearance in a group of 

 shark suckers Echeneis naucrates b of interest. These 

 fish attach themselves to the belly of a shark by 

 means of a modified dorsal fin that has been trans- 

 formed into a suction plate. They are not strictly 

 parasitic, since they derive no nourishment from the 

 body of their host; the latter merely serves as a 

 vehicle to carry them to their food supply. Three of 

 these fish measuring nearly 3 feet in length were 

 caught off the coast of New Jersey and exhibited 

 for several weeks at a seaside resort. They were 

 then transferred to the Fairmount Park Aquarium 

 in the City of Philadelphia, where we had an op- 

 portunity to study them. The fish were kept in a 

 large tank of aerated sea water and fed a diet of 

 fresh shrimp, oysters, clams, and chopped fish. Ap- 

 proximately 6 weeks after arrival, a pink translu- 

 cent, coarsely lobulated tumor appeared on the floor 

 of the mouth in one of the fish. The animal was 

 subsequently sacrificed, at which time the tumor 

 measured 4x3x2.5 cm. almost filled the oral cavity, 

 and obstructed the free flow of water over the gills 

 (Fig. 16). Microscopically the tissue proved to be 

 thyroid, consbting in part of greatly dilated acini 

 filled with marginally vacuolated colloid and lined 

 by cuboidal or columnar epithelium, which formed 

 occasional low papillary projections (Fig. 18). Alter- 

 nating with the large colloid spaces were areas in 

 which the acini were very small. Thyroid tbsue was 

 found between lamellae of bone (Fig. 17), but there 

 was nothing to suggest that thb represented an in- 

 vasion of the bone. The hbtologic picture closely re- 

 sembled the hyperplasia with extensive colloid stor- 

 age frequently observed in non-toxic colloid goiters 

 of man. Bits of tissue were inoculated into the 



anterior chamber of the eyes of three goldfish Car^s- 

 sius tturatus and six large frogs Rama pipiens, but 

 they grew in none and were rapidly resorbed 



A year later the second of these 3 fish bad de- 

 veloped a goiter which in size and structure dosdy 

 resembled the first. Three weeks thereafter 13 

 shark suckers, apparently free of gtuters, were re- 

 ceived from the New York City Aquarium and 

 placed in the same tank with the one remaining 

 shark sucker. Within S months, six of these fish 

 showed marked enlargement of the thyroid (Fig. 

 19) ; after another 5 months all the fish were simi- 

 larly affected. In all but one fish the goiters were 

 confined to the oral cavity, measured between 1 and 

 3 cm. in diameter, and varied in color from pale 

 pink to bright red. In the single remaining fish the 

 thyroid had extended backward beneath each oper- 

 culum, lifting that structure away from the side of 

 the body. The animal rested upside down on the 

 bottom of the tank, apparently to avoid further 

 pressure on its gilb and to facilitate breathing. 



The etiology of the thyroid enlargement in these 

 fishes b obscure. The oxygenation of the water ap- 

 peared adequate. The iodine rich diet of shrimp, 

 clams, and fish, which acted as a cure in the cases of 

 goiter in trout reported by Marine, was apparently 

 without effect. In none of the other marine fishes 

 kept under identical conditions in the aquarium did 

 goiters appear, nor were they known to occur in the 

 fresh water fishes exhibited in the same buQdiog. 

 The goiters of the shark suckers may be a response 

 to some metabolic idiosyncrasy of these fish. Thb 

 view b strengthened by the report of an official who 

 stated that during his service of over twenty years 

 he had frequently observed thb lesion in the shark 

 sucker, but never in any other fishes.* 



AbatractA of other reported casca of tJi7roi4 twaora 



GiutuTH, 1902: A fiN-e year old sahnoa Sdmo 

 solar and 3 rainbow trout Sdmo iridmu eadi bore a 

 tumor the siie of a walnut, that projected beyood both 

 gill clefts and appeared to have started at the apex of 

 the lecood branchial arch. On section the tumors wcfe 

 homogeneous, pale pink in color and soft b coMistency. 

 A fibrous capsule surrounded them, and connective tissue 

 trabeculae extended from the capsule into the tumor 

 parenchyma. The alveoli were irregular and Ibed by 

 columnar or cuboidal epithelial celk. The tnmon were 

 well vascularised and frequent hemorrhages were pres- 

 ent. Although the author identifies the mass as aa en- 

 dothelioma, it probably represents a 



•WewWito 

 Dr. RobMtO. 

 Puk A<|aaifcnai who 

 lag iptdrnms at oar 



oar grateful apprKhtioa of tht bl« 

 •f tha 



