K. Earnestkoons et al., INVASIVE WALLEYE DERMAL SARCOMA IN LABORATORY-MAINTAINED WALLEYES STIZOSTEDION-VITREUM, Diseases of aquatic organisms, 24(3), 1996, pp. 227-232
Walleye dermal sarcoma (WDS) was first described as a multifocal cutan
eous neoplasm of walleyes Stizostedion vitreum in Oneida Lake, New Yor
k, USA. The neoplasm was subsequently shown to be caused by a type C r
etrovirus. We have successfully transmitted the neoplasm in laboratory
-maintained young-of-the-year (YOY) walleyes in a number of pathogenes
is studies over the past 6 yr. Neoplasms in these laboratory trials we
re typical of those superficial neoplasms observed in adult feral wall
eyes. A transmission study was begun summer 1994 using 9 wk old walley
es. Starting at 56 d and continuing throughout the experiment, injecte
d fish developed grossly visible, multiple small white skin masses tha
t varied from 0.5 to 10 mm in diameter. These masses appeared on the s
kin of the head, back, flank, fins and lips. Histopathological examina
tion revealed that some of these neoplasms, especially those collected
at 84 d and beyond, did not remain cutaneous, but were locally invasi
ve and replaced normal tissue, primarily muscle. One neoplasm on the h
ead of a young walleye had deformed the brain and had invaded the skul
l. Due to the unusual invasive nature of the microscopic lesions of th
e neoplasm, these findings are reported.