World Health Organisation Classification of Lymphoid Tumours in Veterinary and Human Medicine: a Comparative Evaluation of Gastrointestinal Lymphomas in 61 Cats.

To diagnose and classify the various entities of lymphomas, the World Health Organisation (WHO) classification is applied in human as well as in veterinary medicine. We validated the concordance of these classification systems by having a veterinary and human pathologist evaluate gastrointestinal lymphoma tissue from 61 cats. In 59% of all cases, there was a match between their respective diagnoses of the lymphoma subtype. A complete consensus between the two evaluators was obtained for all samples with a diagnosis of diffuse large B-cell lymphoma, T-cell anaplastic large cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. A corresponding diagnosis was also made in the majority of samples with enteropathy associated T-cell lymphoma (EATL) type II, although this subtype in cats has similarities to the 'indolent T-cell lymphoproliferative disorder of the gastrointestinal tract', a provisional entity newly added to the revised human WHO classification in 2016. Very little consensus has been found with cases of EATL type I due to the fact that most did not meet all of the criteria of human EATL I. Hence, the human pathologist assigned them to the heterogeneous group of peripheral T-cell lymphomas (not otherwise specified). Consequently, concrete guidelines and advanced immunophenotyping based on the model of human medicine are essential to differentiate these challenging entities in veterinary medicine.

Melting curve analysis in canine lymphoma by calculating maximum fluorescence decrease.

PARR is widely used in the diagnostics of canine lymphoma. In human and veterinary medicine, melting curve analysis (MCA) has successfully been introduced to facilitate the process. Since visual interpretation of melting curves can be rather subjective, the purpose of this study was to develop an objective interpretation of melting curves by calculating the maximum fluorescence decrease (dFmax ) within a defined rise of temperature. Lymph node aspirates and blood of 34 dogs with lymphoma and 28 control dogs were tested. 27/34 lymphoma cases were correctly detected to be monoclonal (sensitivity 79%). 2/28 control dogs showed a monoclonal rearrangement (specificity 93%). B- and T-cell neoplasia were still detectable using DNA amount as low as 10 ng. In serial dilutions of tumor DNA with DNA of normal tonsils, the detection limit was 25% for B-cell lymphomas and 100% for T-cell lymphoma, suggesting that PCR conditions could still be optimized.

European canine lymphoma network consensus recommendations for reporting flow cytometry in canine hematopoietic neoplasms.

BACKGROUND: Flow cytometry (FC) is assuming increasing importance in diagnosis in veterinary oncology. The European Canine Lymphoma Network (ECLN) is an international cooperation of different institutions working on canine lymphoma diagnosis and therapy. The ECLN panel of experts on FC has defined the issue of reporting FC on canine lymphoma and leukemia as their first hot topic, since a standardized report that includes all the important information is still lacking in veterinary medicine. METHODS: The flow cytometry panel of the ECLN started a consensus initiative using the Delphi approach. Clinicians were considered the main target of FC reports. A panel of experts in FC was interrogated about the important information needed from a report. RESULTS: Using the feedback from clinicians and subsequent discussion, a list of information to be included in the report was made, with four different levels of recommendation. The final report should include both a quantitative part and a qualitative or descriptive part with interpretation of the salient results. Other items discussed included the necessity of reporting data regarding the quality of samples, use of absolute numbers of positive cells, cutoff values, the intensity of fluorescence, and possible aberrant patterns of antigen expression useful from a clinical point of view. CONCLUSION: The consensus initiative is a first step toward standardization of diagnostic approach to canine hematopoietic neoplasms among different institutions and countries. This harmonization will improve communication and patient care and also facilitate the multicenter studies necessary to further our knowledge of canine hematopoietic neoplasms. © 2016 International Clinical Cytometry Society.

Immunophenotype of Peripheral Blood Lymphocytes in Dogs with Inflammatory Bowel Disease.

BACKGROUND: Inflammatory bowel disease (IBD) is common in dogs. Despite the known importance of intestinal lymphocytes in its pathogenesis, little is known about the role of peripheral blood lymphocytes (PBLs) in IBD. OBJECTIVES: The aims of this study were (1) comparison of PBLs analyzed by flow cytometry (FCM) in IBD dogs and healthy controls and (2) comparison of PBLs in IBD dogs at the time of diagnosis and in dogs in clinical remission. ANIMALS: Whole blood samples of 19 IBD dogs at the time of diagnosis and blood samples of 6 dogs in clinical remission were collected. Ten healthy dogs served as controls. METHODS: In this prospective observational study, PBLs were analyzed with multicolor FCM by staining with a panel of anticanine and cross-reactive monoclonal antibodies against T- and B-cell differentiation antigens, including CD45, CD3, CD4, CD8α, CD8ß, TCRαß, TCRγδ, CD79αcy, and CD21. RESULTS: The IBD patients' PBLs had significantly decreased percentages of TCRγδ+ T lymphocytes (median: healthy dogs, 3.32; IBD dogs, 0.97; P = 0.03) and CD21+ B cells (median: healthy dogs, 27.61; IBD dogs, 17.26; P = 0.04). There were no significant differences in PBLs between pretreatment and follow-up samples. CONCLUSIONS AND CLINICAL IMPORTANCE: The differences between PBLs in healthy and IBD dogs analyzed by FCM indicate an imbalance of lymphocytes with different immunologic functions and emphasize the potential value of this technique in a larger cohort of dogs. The PBLs did not differ between IBD dogs before treatment and clinically well-controlled dogs after treatment.

Characterization of a PCR-based lymphocyte clonality assay as a complementary tool for the diagnosis of feline lymphoma.

Differentiation between resident mature lymphocyte populations and small cell lymphoma cannot be made by cytological review alone and remains challenging in histopathological review. These cases warrant application of complementary tools like PCR-based immunoglobulin (IG) and T-cell receptor (TCR) clonality testing for confirmation. In this prospective study, diagnostic sensitivity and specificity of different primer sets for routine diagnosis of feline TCR gamma (TCRG) and complete IG heavy chain (IGH) gene rearrangements were assessed. Fine needle aspirates from 20 feline lymphoma cases and lymph node material from 10 cats without hematopoietic neoplasia were subjected to clonality testing. Feline lymphoma cell lines and previously confirmed patient material served as positive control. Detection limits for clonal populations within a polyclonal background was 90% for B-cells and 50% for T-cells. Diagnostic sensitivity and specificity of the clonality assay were 70% and 90%. Overall diagnostic accuracy was 77%, positive predictive value 93% and negative predictive value 60%.

Detection of monoclonality in intestinal lymphoma with polymerase chain reaction for antigen receptor gene rearrangement analysis to differentiate from enteritis in dogs.

The diagnosis of canine intestinal lymphoma by morphological examination is challenging, especially when endoscopic tissue specimens are used. The utility of detection of antigen receptor gene rearrangement by polymerase chain reaction (PARR) in canine lymphoma has been well established, but its usefulness to distinguish enteritis and intestinal lymphoma remains unclear. In this retrospective study we assessed clonality of 29 primary canine intestinal lymphoma, 14 enteritis and 15 healthy control cases by PARR analysis, using formalin-fixed, paraffin-embedded full-thickness tissue specimens. We could detect monoclonal rearrangements in 22 of 29 canine intestinal lymphomas [76%; 95% confidence interval (CI) 56-90%] and polyclonal rearrangements in all of the enteritis and healthy control cases (100%; CI 88-100%). We revealed a predominance of T-cell phenotype compared to B-cell phenotype (85%; CI 65-96% and 15%; CI 4-35%, respectively). We showed that PARR analysis contributes to differentiation of canine intestinal lymphoma from enteritis and to phenotyping of lymphomas.

Pyogranulomatous panniculitis in ferrets (Mustela putorius furo) with intralesional demonstration of Pseudomonas luteola.

One ferret (Mustela putorius furo) from Finland and two ferrets from Austria, aged 1-4.5 years and of both genders, were presented with pyogranulomatous subcutaneous inflammation affecting the inguinal, preputial and femoral regions, respectively. Histologically, microorganisms were detected within the lesions. The organisms had a capsule that stained positively by the periodic acid-Schiff reaction. Pseudomonas spp. were cultured from the lesions in two cases. In the third case, electron microscopy revealed a prokaryotic organism surrounded by an electron lucent matrix. 16S rRNA gene sequencing showed highest sequence homology to Pseudomonas luteola in all three cases. In combination with recent reports of pleuropneumonia in ferrets due to P. luteola infection, these cases might indicate a predisposition of ferrets for infection by these bacteria.

Platelet-derived growth factors and receptors in Canine Lymphoma.

Platelet-derived growth factors (PDGFs) belong to a family of polypeptide growth factors that signal through cell surface tyrosine kinase receptors to stimulate growth, proliferation and differentiation. Platelet-derived growth factor receptors (PDGFRs) are also considered important targets for specific kinase inhibitors in the treatment of several human tumours. The aim of this study was to investigate the role of PDGF-A, PDGF-B, PDGFR-α and PDGFR-ß in canine lymphoma by determining gene and protein expression in lymph nodes of dogs with diffuse large B-cell lymphoma (DLBCL), peripheral T-cell lymphoma (PTCL), T-lymphoblastic lymphoma (T-LBL) and in healthy control dogs. One lymph node was also studied at the end of therapy in a subset of dogs in remission for DLBCL. In controls, PDGF-A, PDGFR-α and PDGFR-ß mRNA levels were significantly higher than in DLBCLs, PTCLs and T-LBLs. However, PDGFR-α and PDGFR-ß were minimally expressed by lymphocytes and plasma cells in normal lymph nodes as determined by immunohistochemistry, while neoplastic B and T cells showed the highest score (P <0.05). This discordant result may be compatible with the constitutive expression of these molecules by endothelial cells and fibroblasts in normal lymph nodes, thereby influencing gene expression results. Furthermore, these cells were not included in the immunohistochemical analysis. Similarly, dogs with DLBCL that were in remission at the end of therapy showed significantly higher gene expression of PDGFs and receptors than at the time of diagnosis and with an opposite trend to the protein assay. PDGF-B protein and mRNA were overexpressed in PTCLs and T-LBLs when compared with DLBCLs and controls (P <0.05). Additionally, there was a correlation between protein expression of PDGF-B and both PDGFRs in PTCLs and T-LBLs, suggesting an autocrine or paracrine loop in the aetiology of aggressive canine T-cell lymphomas. These data provide a rationale for the use of PDGFR antagonists in the therapy of aggressive T-cell lymphomas, but not in DLBCLs.

Phenotypic characterization of canine intestinal intraepithelial lymphocytes in dogs with inflammatory bowel disease.

BACKGROUND: Many dogs suffering from inflammatory bowel disease (IBD) are presented to veterinary clinics. These patients are diagnosed based on a history of chronic gastrointestinal signs and biopsy-confirmed histopathologic intestinal inflammation. Intestinal intraepithelial lymphocytes (IEL) are part of the first line of defense in the gastrointestinal immune system. Alterations in IEL subsets may play a role in the pathogenesis of IBD. HYPOTHESIS: The aim of this study was to characterize the phenotypes of IEL in dogs with IBD compared with healthy control dogs. ANIMALS: Intestinal intraepithelial lymphocytes subpopulations of control dogs (n = 5) obtained from endoscopic biopsies (EB) were compared to those obtained from full thickness biopsies (FTB) on the same day. In addition, the phenotypes of IEL from FTB of control dogs (n = 10) were compared with EB of IBD dogs (n = 10). Each participant was scored clinically using the canine inflammatory bowel disease activity index (CIBDAI), and all samples were graded histopathologically. Three-color flow cytometry of isolated IEL was performed using monoclonal antibodies against T- and B-lymphocyte subpopulations. RESULTS: No significant differences in the composition of IEL subpopulations were found in control dogs based on method of biopsy. The IBD dogs had significantly higher CIBDAI and histopathologic scores compared with control dogs and their IEL contained a significantly higher frequency TCRγδ T-cells. CONCLUSIONS AND CLINICAL IMPORTANCE: Endoscopic biopsies provide suitable samples for 3-color flow cytometry when studying canine intestinal IEL and IBD patients show significant changes of major T-cell subsets compared to healthy control dogs.