An epizootic of an epitheliotropic lymphoblastic lymphoma in coho salmon Oncorhynchus kisutch

Juvenile coho salmon Oncorhynchus kisutch reared at a freshwater hatchery on Vancouver Island, Canada, exhibited high, chronic losses associated with an epitheliotropic lymphoblastic lymphoma of thymic origin. Cumulative mortality of 45% occurred over an 8 mo period in one year class. The disease wa...

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Bibliographic Details
Published in:Diseases of aquatic organisms 1991-06, Vol.11 (1), p.1-8
Main Authors: KIESER, D, KENT, M. L, GROFF, J. M, MCLEAN, W. E, BAGSHAW, J
Format: Article
Language:English
Subjects:
Animal tumors. Experimental tumors
Biological and medical sciences
Freshwater
Medical sciences
Oncorhynchus kisutch
Spontaneous animal tumors
Tumors
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Summary:Juvenile coho salmon Oncorhynchus kisutch reared at a freshwater hatchery on Vancouver Island, Canada, exhibited high, chronic losses associated with an epitheliotropic lymphoblastic lymphoma of thymic origin. Cumulative mortality of 45% occurred over an 8 mo period in one year class. The disease was observed in the fish until release from the hatchery for seawater migration. Saltwater challenge tests indicated that the affected fish had impaired osmoregulation and thus poor seawater survival was expected. Histological examination of the moribund fish revealed a marked proliferation of neoplastic lymphoid cells in the thymus. The cells infiltrated the gills, the integument of the opercular cavity, and the skin around the nares and eyes. The neoplastic cells were oval with a moderate amount of finely granular eosinophilic cytoplasm, and had a centrally located nucleus.
ISSN:0177-5103
DOI:10.3354/dao011001