Clonality Testing in Veterinary Medicine: A Review With Diagnostic Guidelines

Area of Science:

• Veterinary Pathology
• Molecular Diagnostics
• Immunology

Background:

• Accurate differentiation of reactive and neoplastic lymphoid proliferations is critical for appropriate prognosis and treatment in veterinary medicine.
• Molecular clonality assays, by assessing lymphocyte antigen receptor gene rearrangements, offer a tool to aid this distinction.
• Challenges exist in interpreting these assays, especially in atypical cases or limited sample types.

Purpose of the Study:

• To familiarize veterinary pathologists and clinicians with the principles, potential pitfalls, and limitations of molecular clonality testing.
• To provide diagnostic guidelines for the harmonization of clonality testing in veterinary medicine.

Main Methods:

• Review of existing literature on molecular clonality assays in veterinary diagnostics.
• Analysis of the application of clonality testing in various lymphoid proliferation scenarios.
• Discussion of interpretational complexities and sources of variability.

Main Results:

• Molecular clonality assays are valuable adjuncts for diagnosing lymphoid proliferations, particularly in challenging cases like small tissue fragments or fluid samples.
• These assays can also monitor neoplastic clone evolution over time and across different sites.
• Significant challenges include interpreter dependency, lack of standardized practices, and varied terminology, impacting reproducibility.

Conclusions:

• Molecular clonality testing is an indispensable tool but requires careful interpretation alongside clinical, morphologic, and immunophenotypic data.
• Standardization of laboratory practices and interpretational guidelines is essential to improve the reliability and reproducibility of clonality testing in veterinary medicine.
• This review provides a foundation for future harmonization efforts, aiming to enhance diagnostic accuracy.