Cross Lineage Rearrangement in Feline Enteropathy-Associated T-cell Lymphoma.

Area of Science:

• Veterinary Pathology
• Canine and Feline Oncology
• Molecular Diagnostics

Background:

• Feline enteropathy-associated T-cell lymphoma (EATL) type II presents diagnostic challenges, often mimicking inflammatory conditions due to small T-cell infiltration.
• Polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR) is crucial for differentiating EATL from inflammation by assessing T-cell receptor gamma (TCRG) and immunoglobulin heavy chain (IGH) gene rearrangements.

Purpose of the Study:

• To determine the incidence of cross lineage rearrangement in feline EATL type II.
• To evaluate the utility of PARR testing in diagnosing feline EATL type II, particularly when TCRG gene rearrangements are polyclonal.

Main Methods:

• A diagnostic algorithm integrating histology, immunohistochemistry, and PARR testing was employed.
• Analysis of 92 feline cases diagnosed as EATL type II between January 2013 and June 2014.
• Assessment of both TCRG and IGH gene rearrangements using PARR.

Main Results:

• Cross lineage rearrangement was identified in 8.7% (8 of 92) of feline EATL type II cases.
• PARR testing for the IGH gene proved valuable in diagnosing cases with suspected EATL type II and polyclonal TCRG rearrangement.
• This highlights the complexity of lymphocyte clonality in feline EATL.

Conclusions:

• Cross lineage rearrangement is an important consideration in the diagnosis of feline EATL type II.
• Integrating PARR, especially IGH gene analysis, with traditional methods improves diagnostic accuracy.
• Accurate differentiation of EATL from inflammation is critical for appropriate feline patient management.