Clonality testing in the lymph nodes from dogs with lymphadenomegaly due to Leishmania infantum infection

Abstract

IntroductionIn southern European countries, multicentric lymphoma and leishmaniosis are the main differential diagnoses in dogs presented with generalized lymphadenomegaly. The cytological examination is in some cases inconclusive and polymerase chain reaction (PCR) for antigen receptor rearrangement (PARR) has become a common method to confirm or rule out a lymphoproliferative neoplasia. According to the literature, leishmaniosis may lead to clonal arrangements and therefore to a false diagnosis of lymphoma, but this assumption is made from a single leishmania infected dog. Therefore, the objective of this study was to prospectively evaluate results from PARR in dogs with lymphadenomegaly due to clinical leishmaniosis at the moment of diagnosis.Materials and methods31 dogs with a diagnosis of leishmaniosis based on the LeishVet guidelines were included in the study. Samples from enlarged lymph nodes were taken for cytological examination, clonality testing and Leishmania infantum PCR.ResultsAll 31 dogs had medium to high positive antibody titers against Leishmania spp. and 30/31 had a positive Leishmania PCR from the lymph node. A polyclonal arrangement for B cells (immunoglobulin heavy chain gene) and T cells (T-cell receptor gamma chain gene) antigen receptors was found in 28/31 dogs. Two out of 31 dogs showed a monoclonal arrangement for Ig with high (1:2) and low (1:7) polyclonal background respectively; and one of the 31 dogs showed a monoclonal arrangement for T cell receptor with low (1:3) polyclonal background.ConclusionInfections with Leishmania infantum resulted in clonal rearrangement, and therefore in a possible false diagnosis of lymphoma, in 3 out of 31 dogs (9.7%). Although, PARR is a useful method to differentiate lymphoma from reactive lymphoid hyperplasia in dogs with leishmaniosis, mono-/biclonal results should be interpreted carefully, especially in the presence of any degree of polyclonal background, and together with other clinicopathological findings.

Canine lymphoma and vector‐borne diseases: Molecular and serological evaluation of a possible complicity

“…In our case series, clonality assessment was performed for all samples (results not showed), being all monoclonal, and in accordance with the previous IHC phenotype. No possible monoclonal peak with a polyclonal background due to L. infantum 58 was observed.…”

A newly established canine NK‐type cell line and its cytotoxic properties

“…PCR for antigen receptor rearrangement (PARR) Test was performed commercially by Laboklin Polska sp.z o.o. according to the guidelines described in Reference 20.…”

Doing more with less: multiple uses of a single slide in veterinary cytology. A practical approach

“…The DNA product assessed by capillary electrophoresis can display a single length (monoclonal peak), thus corresponding to a monoclonal neoplastic proliferation, or display multiple lengths (polyclonal expansions), as expected in inflammatory conditions (Guillen et al 2021 ). Several primers are used for the complementary region 3 of T cell receptor and immunoglobulin heavy chain genes (e.g., Melendez-Lazo et al 2019 ; Waugh et al 2016 ). Recent studies have reported high sensitivity with figures over 80% for different types of lymphomas (Goto-Koshino et al 2015 ; Vessieres et al 2018 ; Waugh et al 2016 ).…”

“…Recent studies have reported high sensitivity with figures over 80% for different types of lymphomas (Goto-Koshino et al 2015 ; Vessieres et al 2018 ; Waugh et al 2016 ). Specificity is usually high but can be negatively affected by infectious diseases such as ehrlichiosis or leishmaniasis (Burnett et al 2003 ; Melendez-Lazo et al 2019 ). In the latter, 10% of animals may present monoclonal or biclonal patterns, leading to false diagnosis.…”