Differential diagnosis of lymphoid and myeloid tumors in the chicken (slide set and text)

Authors: Dunn, John; GIMENO, ISABEL - North Carolina State University; WAKENELL, PAT - Purdue University; SATO, YUKO - Purdue University

Submitted to: American Association of Avian Pathologists
Publication Type: Other
Publication Acceptance Date: 10/27/2021
Publication Date: 10/27/2021
Citation: Dunn, J.R., Gimeno, I.M., Wakenell, P., Sato, Y. 2021. Differential diagnosis of lymphoid and myeloid tumors in the chicken (slide set and text). American Association of Avian Pathologists. 2nd edition.

Interpretive Summary: This documentation and slide study set is to provide a conceptual basis for the differential diagnosis of lymphoid and myeloid tumors in chickens and may also serve as a teaching aid. It is directed primarily to the academician although students and field veterinarians should also find the information useful. No attempt is made to illustrate all lesions associated with tumor virus infection in chickens as this is considered in other slide sets. An attempt is made to discuss diagnostic methods on two levels. Standard criteria (level 1) are based on gross and histological lesions which can be ascertained by virtually all diagnostic laboratories. Advanced criteria (level 2) involve more specialized techniques and, in some cases, may require the assistance of reference laboratories. The detection of virus, viral antigens or their antibodies is a subset of advanced criteria. Whereas standard criteria may be suitable for presumptive diagnoses in many cases, advanced criteria may be needed to establish a definitive diagnosis.

Technical Abstract: This slide set and associated text is to assist diagnosticians and veterinary pathologists in making accurate diagnoses of field cases in chickens where lymphoid or myeloid tumors are suspected. Lesions and other diagnostic features that distinguish Marek’s disease (MD), lymphoid leukosis (LL), myeloid leukosis (ML) and the bursal and nonbursal lymphomas associated with reticuloendotheliosis (RE) are discussed and illustrated. Differentiation of these neoplasms from nonneoplastic syndromes and assorted other tumors is also discussed. Emphasis is placed on diagnostic strategies rather than specific procedures. A system is presented by which a diagnostic case is first assigned to one of four clinical types based mainly on gross lesions and age. This approach reduces the number of possible conditions to be considered, thus simplifying the process. Differential diagnosis continues to be based primarily on gross and microscopic lesions. Additional tests of proven value for diagnosis include determination of T-cell and B-cell frequency, determination of viral antigen expression, and quantitative PCR (qPCR). Tests for detection of specific viruses or their antibodies have only limited value but can be adjuncts to other methods in some cases. Several additional tests with potential value are presented to encourage further development and field testing by reference laboratories. Some unpublished data relevant to diagnosis is presented in summary form.