ABSTRACT
The vast majority of neoplasms from cold-blooded vertebrates in the marine ecosystem submitted to the Registry of Tumors in Lower Animals (RTLA) or described in the published literature were from specimens collected in the estuarine and neritic zones. Hematopoietic neoplasms appear to have been caused by viruses. Clusters of connective tissue neoplasms have circumstantial evidence for a viral cause. Neoplasms arising from both peripheral nerve sheath cells and from pigment cells appear to have a genetic basis that can be influenced or activated by several different factors. Epidermal neoplasms seem to be of several basic types including the plaque type where evidence favors a viral etiology and the smooth lobular type where evidence favors a chemical etiology except in Japanese salmonids. Tumors originated in skin, invaded underlying muscle, and ultimately metastasized to kidney, spleen, and liver in that order.
