Abstract

Neoplasia is an uncommon finding in elasmobranchs, with a 0.4% prevalence.^1,2 An adult female white-spotted bamboo shark (Chiloscyllium plagiosum) from the Vancouver Aquarium collection was noted to be significantly smaller than conspecifics and very thin despite a normal appetite. This individual was removed from the 170,000 L closed, recirculating saltwater system but succumbed prior to diagnostic work-up. Gross necropsy revealed numerous 2–15 mm firm, white, often coalescing nodules that protruded from the surface of the liver. These nodules extended throughout the parenchyma. A single, similar 5-mm diameter white nodule was present within the spleen. Histopathology of liver and spleen identified an infiltrative, non-encapsulated, densely cellular neoplasm comprised of sheets of round cells with prominent large nuclei and scant amphophilic to basophilic cytoplasm. The cell membranes were variably distinct and mitotic index was five per ten 400x high powered fields. The tumors were diagnosed as lymphoma. This neoplastic process has previously been reported in two elasmobranchs -one in a sandbar shark (Carcharhinus plumbeus), and the other in a captive bonnethead shark (Sphyrna tiburo).^1,3 We believe this is the first report of a round cell tumor suspected in the ultimate demise of a display elasmobranch.

Acknowledgements

The authors would like to thank Sandra Etheridge and Joanne Taylor for slide preparation, Linda Hokanson for her assistance with the poster and the Tropical department staff at the Vancouver Aquarium for their support and expertise.

* Presenting author
+ Student presenter

Literature Cited

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2.  Garner MM. A retrospective study of disease in elasmobranchs. Veterinary Pathology. 2013;50(3):377–89.

3.  Manire CA, Clarke AC, Wert D, Landolfi J. Lymphosarcoma in a captive bonnethead shark, Sphyrna tiburo (L.). Journal of Fish Diseases. 2013;36(4):437–40.