The disease syndromes associated with REV include 1) a runting disease syndrome, 2) chronic neoplasia of lymphoid and other tissues, and 3) acute reticulum cell neoplasia.

[1] Reticuloendotheliosis virus represents a third distinct etiological group of avian viral neoplasms, after Marek's disease and avian leukosis virus.

The various syndromes caused by REV resemble both Marek's and avian leukosis.

To explain them a theory based on iatrogenic origin was proposed.

[4] The American Association of Avian Pathologists maintains a fact sheet on viral tumor diseases.