Neoplasias in Fish: Review of the Last 20 Years. A Look from the Pathology

Abstract

In fish there is an innumerable variety of neoplasias that arise essentially from all cell types. Neolasia here, we will focus on the neoplasias that appear spontaneously in these animals and will not cover the experimentally induced neoplasias and/or the animal models of neoplasias. As for diagnosis, in general, specialists in aquatic organism pathology are not so familiar with the diagnosis of neoplasias. Infectious pathology, as opposed to non-infectious pathology, is the predominant condition in this area and, of course, these are of greater importance because some infectious diseases generate great economic losses, while neoplasias are isolated pathologies, with some exceptions.
 In the last 20 years, 10 neoplasias in different species have been diagnosed in our laboratory, and we reported their characteristics in this paper. We also made a detailed bibliography review and observed how 90 neoplasias among 56 species of teleosteal fish were reported.
 Neoplasias in fish, unlike other diseases, do not generate great losses to aquaculture. However, the true value of neoplastic pathology compared is to better understand the histiogenesis and biological behavior of neoplasias in mammals and humans. Carcinogenesis is generally complex and in most neoplasias in both mammals and fish, the origin is unknown, and it seems that there are many factors that contribute to the onset and growth of neoplasias.

Occurrence of an Abdominal Leiomyosarcoma in the Cyprinus carpio: Optical and Immunohistochemical Study

“…Among 407 neoplasms mentioned [9] of several fish species, none was leiomyosarcoma. In a recent review of neoplasms in fish, none leiomyosarcomas were found in the last twenty years [10]. This report documents a carp abdominal leiomyosarcoma studied with light microscopy and immunohistochemistry.…”

Investigation of extragonadal teratomas in two Poecilia wingei

“…It is assumed that teratomas in fish arise from totipotent cells that differentiate along several germinal pathways (Romano & Pedrosa, 2020). Differences in the localization of teratomas may be due to the different origins of these tumours.…”

“…There are a large number of neoplasms in fish that arise from all types of cells (Romano & Pedrosa, 2020). Fish tumours are generally less aggressive, more differentiated, and less likely to metastasize than tumours of mammals (Groff, 2004; Vergneau‐Grosset et al., 2017).…”

Occurrence of hepatic and splenic lipomas in Nile tilapia (Oreochromis niloticus)

“…Out of the 407 neoplasms cited by Mawdesley‐Thomas (1971) across several fish species, 10 are classified as lipomas, with only 2 of them found in the liver. A more recent review reported that over a 20‐year period of study across various fish pathology laboratories, out of 98 diagnosed neoplasms, only 5 were identified as lipomas (Romano & Pedrosa, 2020). Numerous authors have reported lipomas in different fish species (Ferguson, 1989; Plehn, 1924; Thomas, 1933).…”