Schlumberger and Lucki — Tumors in Fishes 



665 



(31 ) was located on the lower lip of a barbel Barbus 

 vulgaris. It was the size of a hazel-nut and had in- 

 filtrated the floor of the mouth; structures sugges- 

 tive of epithelial pearls were present and mitoses 

 were numerous. 



Fiebiger's report (47) of epitheliomas on the lips 

 of two tench Tinea tinea is of interest in that the 

 tumors occurred in fish from the same pond. The 

 evidence of malignancy is not certain, for the author 

 states that a fairly well preserved basement mem- 

 brane surrounded the extensive epithelial pegs. In 

 wie of Beatti's (7) two cases of epithelioma in 

 croakers, the basement membrane was intact in most 

 regions, though in some areas epithelial pegs pene- 

 trated deeply. In the other this was more marked, 

 and invasion of subcutaneous tissue had taken place. 



We ourselves have been studying a transplantable 

 epithelioma of the lip and mouth of catfish Amei- 

 urus nebuiosus taken from streams near Philadel- 

 phia (122). During a period of 2 years, 166 live 

 tumor-bearing fish were obtained.* Since our pre- 

 vious publication approximately 100 additional cases 

 have been studied. This neoplasm usually occurs as 

 a solitary or multiple, large, red, fleshy mass upon 

 the lips or dental plates (Figs. 8-11); less often it 

 involves other parts of the mouth or the skin. In 

 our series the lips and dental plates were affected in 

 all but 6 cases. All of the neoplasms are grossly 

 ^milar. They are broadly sessile, with a smooth or 

 coarsely nodular surface; in consbtency they are 

 firm and resilient. Most of the tumors average from 

 1 to 2 cm. in diameter, but some are so massive as 

 to prevent closure of the mouth (Fig. 10). In ap- 

 proximately one-half of the cases, both lips or dental 

 plates are involved. In 53, or 60 per cent, of 89 fish 

 the tumors were in direct apposition (Figs. 9 and 

 11). Histologically the tumors consist of closely 

 packed masses of columnar or polyhedral cells, often 

 growing as papillary pegs supported by a delicate 

 richly vascular stroma (Fig. 12). The smaller tu- 

 mors grow outward, with little sign of invasion. 

 Larger growths commonly push broad solid pegs of 

 epithelial cells deep into the subjacent tissues; in 

 some, these pegs are bounded by a well preserved 

 basement membrane, but in the more massive tu- 

 mors they are definitely invasive, and flame-shaped 



* Many of the tumor-bcarinR fi.oh and several hundrpd 

 norma] fish which were used for experimrntal purposes have 

 been fnmitfaed us through the kindncM of Mr. C. R. Buller. 

 CMef Pish Culturist of the Sute Fish Hatchery, at BeDe- 

 font, Pennsylvania, John J. Wopart, Jr., Superintendent of 

 the State Fbh Hatchery at Torrtsdale, Pennsylvania, and 

 the late Dr. Robert O. Van Deusen, Director of the Phila- 

 delphia Aquarium. We wish to express our grateful appicdft- 

 tion to these gentlemen for the aid and advki gi»t 



processes of loosely arranged cells extend far into 

 the subjacent tissues (Fig. 13). In the more in- 

 vasive tumors embdi of neqplastic cdls are often 

 found, though no metastases have been observed. 

 It seems evident that the small, outward growing 

 tumors are early stages (tf a neopUstic prooeM which 

 later asstmies a more mallgnanf character. 



It has been possible to study living tumors almost 

 from the time of their inception. Tumor-bearing 

 fish were maintained under laboratory conditions 

 for periods up to 9 months; during thb time we 

 observed that growth of most of the neoplasms was 

 relatively slow but progressive. The inception and 

 development of appositional growth was sttidied by 

 direct microscopic examination of the mucosal sur- 

 faces. The earliest evidence of neoplastic chai^ 

 was the establishment of a more or less circum- 

 scribed patch of hyperemia on the mticosa. At this 

 time the mucosal surface was smooth and showed no 

 signs of proliferation ; after approximately two wedcs 

 the patch became slightly elevated; one or two 

 months later the local thickening had progressed to 

 the formation of a definite tumor. 



Detailed microscopic study of the blood vessds 

 in vivo brought out the fact that they undergo pro- 

 found alterations during the development of the 

 tumor. At the site of future neoplastic growth they 

 gradually form irregular, wide meshed networks 

 that contrast sharply with the small, imiform capil- 

 lary loc^s of the adjacent normal mucosa. The 

 caliber of the blood channeb in the neoplastic zone 

 varies greatly; some are dilated and bear saccular 

 expansions; others are constricted (Figs. Hand 15). 

 Many of the proliferating vessels have thick walls, 

 whereas others are thin and delicate. In brief, the 

 neoplastic growth is preceded and accompanied by 

 a striking vascular reaction; the number, arrange- 

 ment, and structure of the vessds are compkvouafy 

 atypical. The relation of Uood-vessds to tumor 

 growth has previously been investigated mainly in 

 fixed tissue; the catfish epithelioma provides ma- 

 terial for such an investigation in the living animal. 



Abstract* of other reported cmm of opitheUoma 



Dauwk and PENNBicAinc, 1904: Each of two 

 ver>' large, old aquarium carp Cyprinus catpio de v e l oped 

 a tumor on the dorsum of the head, in front of the eyes 

 Microscopically the lesions were identical and consisted 

 of squamous epithelial ceUi that formed long pegs con- 

 taining central areas of necrosis. The authors legsrded 

 the tumors as squamous ceU cardnonas. 



Bashford, MuiiAV and CXAicn, 1905: These 

 authors mention an epithelioma in a carp CypHmmt 

 carpio but do not give the location. They state that 

 the tumor presented a strikinf resemblance to squamous 



