Use of Fine Needle Aspirates and Flow Cytometry for the Diagnosis, Classification, and Immunophenotyping of Canine Lymphomas

Tumor staging in a Beagle dog with concomitant large B-cell lymphoma and T-cell acute lymphoblastic leukemia

An 8-y-old spayed female Beagle dog was presented with peripheral lymphadenomegaly. Lymph node cytology and flow cytometry led to the diagnosis of large B-cell lymphoma (LBCL). We detected minimal percentages of LBCL cells in peripheral blood and bone marrow samples. However, a monomorphic population of neoplastic cells different from those found in the lymph node was found in the bone marrow. T-cell acute lymphoblastic leukemia was suspected based on flow cytometric immunophenotyping. PCR for antigen receptor rearrangement (PARR) revealed clonal rearrangement of both B-cell and T-cell receptors, and the presence of both neoplastic clones in the lymph node, peripheral blood, and bone marrow. The dog was treated with multi-agent chemotherapy but died 46 d following diagnosis. Tumor staging and patient classification are needed to accurately establish a prognosis and select the most appropriate therapeutic protocol.

Demographic and clinical characteristics of dogs with centroblastic lymphoma

Background and Aim:

Centroblastic lymphoma (CBL) is the most common morphological type of lymphoma found in dogs; it is usually identified through cytology in veterinary clinical practice. This study aimed to identify the demographic and clinical characteristics of dogs with CBL that was diagnosed with cytology and immunocytochemistry.

Materials and Methods:

Dogs with a suspicion of lymphoma were diagnosed by cytology supported by immunocytochemistry with the use of the updated Kiel classification adapted for dogs. During the analyzed time period, 336 lymphomas were diagnosed in dogs, including 171 cases of CBL. Epidemiological and clinical data from the dogs with CBL were provisionally collected.

Results:

The epidemiology analysis revealed an increased risk of CBL in Rottweilers, golden retrievers, and Bernese mountain dogs. At admission, most of the dogs displayed generalized lymphadenopathy with spleen and liver enlargement. The most common hematological abnormality was leukocytosis due to neutrophilia. The most common biochemical abnormality was elevated alanine aminotransferase and alkaline phosphatase activities and selective hypoproteinemia due to hypoalbuminemia.

Conclusion:

Rottweilers, Bernese mountain dogs, and golden retrievers appear to be overrepresented among dogs with CBL. CBL is usually diagnosed at an advanced clinical stage according to the World Health Organization; however, it is usually accompanied by only minor hematological and biochemical abnormalities.

Electrochemiluminescent biosensor for ultrasensitive detection of lymphoma at the early stage using CD20 markers as B cell-specific antigens

Herein, by taking advantage of the special binding of an aptamer to the membrane surface of a B cell and accumulation of the positive charges of a nanocomposite, including luminol-chitosan-platinum nanoparticles (L-Cs-Pt NPs), on the negatively charge of the aptamer phosphate backbone, a sensitive, simple, selective and rapid strategy for the detection of lymphoma cells by a new label-free electrogenerated chemiluminescence (ECL) aptasensor has been introduced. With increasing concentrations of B lymphoma cells, the nanocomposite detaches from the aptamer, leading to a decrease in the ECL of a luminol and H₂O₂ system. With high loading of luminol and Pt NPs on a chitosan, together with the electrocatalytic effect of Pt NPs, enhanced sensitive detection of cancer cells with a limit of detection of 31 cells/mL was achieved. Step-by-step modification and biosensor response to cancer cells was monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and ECL. The aptasensor exhibited excellent specificity for lymphoma cells vs breast cancer (MCF-7) and human embryonic kidney (HEK293) cell lines as potential interferents. Finally, the performance of the aptasensor in blood samples was assessed against a commercial flow cytometric method. Satisfactory results confirmed the applicability of the proposed biosensing platform.

Clinical features of canine nodal T-cell lymphomas classified as CD8+ or CD4-CD8- by flow cytometry

Canine T-cell lymphoma (TCL) encompasses a heterogeneous group of diseases with variable clinical presentation, cytomorphology, immunophenotype, and biologic behaviour. The most common types of TCL in dogs involving peripheral lymph nodes include indolent T-zone lymphoma (TZL) and biologically aggressive peripheral T-cell lymphoma (PTCL). TCL phenotypes can be categorized by expression of the surface antigen molecules CD4 and CD8. The majority of TCL cases are CD4⁺ , with far fewer cases being CD8⁺ or CD4^- CD8^- . The clinical features of CD4⁺ TCLs have been previously described. The less common TCL phenotypes, however, are poorly characterized with little to no information about prognosis. In this retrospective study, we describe and correlate the presenting clinical signs, flow cytometry, and outcomes of 119 dogs diagnosed with nodal, non-TZL, CD8⁺ or CD4^- CD8^- TCL by flow cytometry. Skin lesions present at the time of diagnosis were more commonly observed in the CD8⁺ TCL group. Mediastinal enlargement and/or hypercalcemia were more commonly seen in the CD4^- CD8^- TCL group. Dogs with either CD8⁺ or CD4^- CD8^- TCLs had aggressive clinical disease with median overall survival (OS) times of 198 days and 145 days, respectively. In both groups, neoplastic cell size determined by flow cytometry ranged from small to large, and large cell size was associated with shorter OS times (median OS = 61 days). Cases classified as small cell had a median OS of 257 days. Expression levels of major histocompatibility complex (MHC) class II and CD5 were highly variable among cases but were not prognostically significant in this group of patients.

Global DNA methylation of peripheral blood leukocytes from dogs bearing multicentric non-Hodgkin lymphomas and healthy dogs: A comparative study

Non-Hodgkin lymphomas are among the most common types of tumors in dogs, and they are currently accepted as comparative models of the disease in humans. Aberrant patterns of DNA methylation seem to play a key role in the development of hematopoietic neoplasms in humans, constitute a special mechanism of transcriptional control, and may be influenced by genetic and environmental factors. Blood leukocyte DNA global methylation has been poorly investigated in dogs. The aim of this study is to examine whether peripheral blood global DNA methylation is associated with canine multicentric lymphomas. Peripheral venous blood samples from ten healthy dogs and nine dogs bearing multicentric lymphomas were collected, and the buffy coat was separated. Global DNA methylation was analyzed by High Performance Liquid Chromatography (HPLC) and immunocytochemistry (ICC). In both analyses, leukocytes from dogs with lymphoma presented lower global DNA methylation than in healthy dogs (HPLC: p = 0.027/ 5MeCyt immunoreactivity scores: p = 0.015). Moderate correlation was observed between the results obtained by HPLC and ICC (correlation coefficient = 0.50). For the identification of differently methylated genes between both groups, the Infinium Human Methylation (HM) EPIC BeadChip (850K) was used. Of the 853,307 CpGs investigated in the microarray, there were 34,574 probes hybridized in the canine samples. From this total, significant difference was observed in the methylation level of 8433 regions, and through the homologous and orthologous similarities 525 differently methylated genes were identified between the two groups. This study is pioneer in suggesting that dogs bearing non-Hodgkin lymphoma presented DNA global hypomethylation of circulating leukocytes compared with healthy dogs. Although canine samples were used in an assay developed specifically for human DNA, it was possible to identify differently methylated genes and our results reiterate the importance of the use of peripheral blood leukocytes in cancer research and possible new biomarkers targets.

Comparison of combination l-asparaginase plus CHOP or modified MOPP treatment protocols in dogs with multi-centric T-cell or hypercalcaemic lymphoma

OBJECTIVES

To compare the progression-free survival of dogs with high-grade T-cell lymphoma treated with either a cyclophosphamide, doxorubicin, vincristine and prednisone-based or a modified mechlorethamine, vincristine, prednisone and procarbazine chemotherapy protocol.

MATERIALS AND METHODS

In this retrospective study, cases were selected based on histologic or cytologic diagnosis of lymphoma, T-cell phenotype, hypercalcaemia, or both, and no previous chemotherapy for lymphoma. Treatment was not randomly allocated.

RESULTS

Seventy-three dogs were included in this study: 50 in the cyclophosphamide, doxorubicin, vincristine and prednisone group and 23 in the mechlorethamine, vincristine, prednisone and procarbazine group. The median progression-free survival was 133 days for dogs in the cyclophosphamide, doxorubicin, vincristine and prednisone group and 97 days for dogs in the mechlorethamine, vincristine, prednisone and procarbazine group. When golden retrievers (n = 16) were evaluated -separately, progression-free survival was longer in the cyclophosphamide, doxorubicin, vincristine and prednisone versus mechlorethamine, vincristine, prednisone and procarbazine treatment group (median PFS 154 days versus 70.5 days, respectively).

CLINICAL SIGNIFICANCE

The progression-free survival time for dogs with multi-centric T-cell lymphoma treated with a modified mechlorethamine, vincristine, prednisone and procarbazine protocol was similar to that of dogs treated with cyclophosphamide, doxorubicin, vincristine and prednisone. Further studies, including those evaluating golden retrievers separately, are needed to confirm these findings.

Breed prevalence of canine lymphoma in South Africa

Lymphoma is a common haematopoietic neoplasm in dogs. Several breeds have been shown to have a predisposition to lymphoma; however, very little information exists regarding the South African dog population. This study assessed whether any breed had increased odds of developing lymphoma compared with others, and also investigated the effects of age, sex and neutering status on disease prevalence. Two study populations and their corresponding reference populations were studied retrospectively. Odds ratios (ORs) for lymphoma in 49 dog breeds, together with their 95% confidence intervals (CI), were calculated. Age effect was assessed by calculating ORs for different age categories in one of the populations. The chi-square test was used to evaluate differences in the prevalence of the various sex and neutering categories in one lymphoma population compared with its reference population. Fourteen breeds had significantly increased odds of developing lymphoma, and one breed had significantly decreased odds (p < 0.050). The median ages of the two lymphoma populations were 6.5 and 8.0 years, with the 6.1-9.0 year category having significantly increased odds of developing lymphoma (OR 1.61, CI 1.2-2.16, p = 0.002). In one of the lymphoma populations, higher proportions of males (p = 0.033) and neutered females (p = 0.006) were found when compared with the reference population. These findings suggest that certain breeds in South Africa have a higher risk of developing lymphoma, and that sex hormones may play a role in lymphoma pathogenesis. The findings may provide useful information for pet owners and veterinarians.

Cytodiagnostics of canine lymphomas - possibilities and limitations

Malignant lymphomas are one of the most common malignant tumours occurring in dogs. The basic method of lymphoma diagnosis in human, as well as in canine oncology is histopathology supported by immunohistochemistry. It was suggested that in veterinary medicine excisional biopsy of lymph node and histopathology should be considered only where the cytologic diagnosis is equivocal or needs to be confirmed. There are at least three basic reasons for which cytological examination ought to be accepted as a sufficient and reliable diagnostic method for lymphoma in dogs. Firstly, most dog owners consider the fine-needle biopsy as an acceptable non-harmful method of sample collection. Secondly, an increasing number of studies recommend cytology as an accurate test for diagnosing and subtyping canine lymphoma. Finally, the vast majority of canine lymphoma subtypes belong to 4-5 categories characterized by a typical cytological picture. Immunocytochemical staining of cytological smears gives new diagnostic possibilities, such as detection of markers better characterizing given growth or a potential goal for target therapy in individual cases (for example inhibitors of platelet-derived growth factor).

Development and application of multiple immunofluorescence staining for diagnostic cytology of canine and feline lymphoma

BACKGROUND

Immunophenotyping of canine and feline lymphoma to determine B-cell or T-cell origin is important for predicting prognosis and for development of treatment protocols. For advanced diagnostic cytology tests that can be performed on smears are required to predict the immunophenotype of lymphomas.

OBJECTIVES

The aim of this study was to develop a multiple immunofluorescence (MIF) staining method for the determination of lymphocyte immunophenotype in cytologic specimens, and to evaluate its clinical utility.

METHODS

B cells and T cells were detected using anti-CD79α and anti-CD3 antibodies, respectively, followed by specific fluorescence-labeled secondary antibodies. The MIF staining method was first developed using fresh-frozen sections of normal canine lymph nodes. The optimal fixative, the necessity of antigen retrieval (AR), and the optimal concentration of the antibodies were determined. The MIF method was then applied to smears of normal lymph nodes, and to clinical samples from dogs and cats with lymphoma. The MIF results were compared to genetic clonality results.

RESULTS

B and T cells were detected based on specific fluorescence in frozen sections, using formalin fixation without AR. Specific fluorescence was also detected in smears from normal lymph nodes and lymphomas, and the immunophenotypes predicted from this MIF staining method completely corresponded to those from genetic clonality analysis.

CONCLUSIONS

The MIF staining method that we developed in this study effectively distinguished lymphocyte immunophenotypes with high specificity and sensitivity using a single smear sample, and was useful as a diagnostic tool for canine and feline lymphoma.

Gamma delta T-cell large granular lymphocyte lymphoma in a dog

A 2-year and 6-month-old female neutered Labrador Retriever with Horner syndrome, megaesophagus, and a mediastinal mass was referred to the Queen Mother Hospital for Animals of the Royal Veterinary College. A large granular lymphocyte (LGL) lymphoma was diagnosed on cytology; flow cytometric analysis revealed a γδ T-cell phenotype (CD3+, CD5+, CD45+, TCRγδ+, CD4-, CD8-, CD34-, CD21-). Chemotherapy was started with a combination of lomustine, vincristine, procarbazine, and prednisolone, followed by bleyomicin. Euthanasia was elected by the owners, due to progressive deterioration and lack of quality of life, 28 days after diagnosis. This is the first cytologic and immunophenotypic characterization of a canine γδ T-cell lymphoma with LGL morphology and probably of mediastinal origin. The role of chemotherapy in delaying the disease progression remains unknown.

Evaluation of lymph node aspirates at diagnosis and relapse in dogs with high-grade multicentric lymphoma and comparison with survival time

BACKGROUND

Canine high-grade multicentric lymphoma, a common disease with variable response to chemotherapy, is often diagnosed using cytology.

OBJECTIVES

The purpose of the study was to compare cytologic features of canine peripheral lymph node aspirates collected at diagnosis and at relapse, and evaluate their usefulness in predicting survival.

METHODS

Cytologic scoring based on a rubric and nuclear morphometry analyses were performed on cytologic smears collected at diagnosis and at relapse. Scores at diagnosis and relapse were compared by paired t-test and evaluated in relation to time from diagnosis to remission, remission to relapse, relapse to death, and total survival time, using the Cox proportional-hazards regression model.

RESULTS

Number of mitoses and total cytologic score were significantly higher at relapse compared to diagnosis (P < .05). None of the nuclear morphometry measures were significantly different between diagnosis and relapse. The presence of binucleated or multinucleated cells at diagnosis was associated with a shorter remission and decreased total survival (P < .05). Increased mean nucleoli at relapse was associated with longer remission and total survival (P < .05). Increased minimum nuclear radius and diameter at diagnosis were associated with a decreased time from relapse to death (P < .05). Several nuclear morphometry measures at relapse were associated with a shorter time from diagnosis to remission (P < .05).

CONCLUSIONS

Number of mitoses and total score were higher at relapse than at diagnosis in canine lymphoma. The presence of binucleated or multinucleated cells at diagnosis may be useful as indicator of a poor prognosis. Further studies including a larger number of cases are required to reinforce the prognostic values of these cytologic features.

Liquid-based cytology and cell block immunocytochemistry in veterinary medicine: comparison with standard cytology for the evaluation of canine lymphoid samples

Liquid-based Cytology (LBC) consists of immediate wet cell fixation with automated slide preparation. We applied LBC, cell block (CB) and immunocytochemistry to diagnose canine lymphoma and compare results with conventional cytology. Samples from enlarged lymph nodes of 18 dogs were collected and fixed in preservative solution for automated slide preparation (LBC), CB inclusion and immunophenotyping. Two CB techniques were tested: fixed sediment method (FSM) and agar method (AM). Anti-CD79a, anti-Pax5, anti-CD3 and anti-Ki67 were used in immunocytochemistry. LBC smears showed better nuclear and nucleolar definition, without cell superposition, but presented smaller cell size and worse cytoplasmic definition. FSM showed consistent cellular groups and were employed for immunocytochemistry, while AM CBs presented sparse groups of lymphocytes, with compromised analysis. Anti-Pax-5 allowed B-cell identification, both in reactive and neoplastic lymph nodes. Our preliminary report suggests that LBC and FSM together may be promising tools to improve lymphoma diagnosis through fine-needle aspiration.

Immunophenotypic characterization of canine malignant lymphoma: a retrospective study of cases diagnosed in Poland Lower Silesia, over the period 2011-2013

Lymphoma is the most frequently diagnosed cancer of the canine haematopoietic system. In this study, the flow cytometry and polymerase chain reaction (PCR) analysis were used to characterize a series of canine lymphomas in detail. The aim of this study was to determine the incidence of B- and T-cell high-grade lymphomas and their immunophenotypic characterization in Lower Silesia, Poland. The results show that the frequency of each type of lymphoma is 71% for B-cell and 17% for T-cell lymphomas. In two cases the PCR techniques confirmed the presence of simultaneous double gene rearrangements of the BCR and TCR receptors.

Flow cytometric characterization and clinical outcome of CD4+ T-cell lymphoma in dogs: 67 cases

Background

Canine T‐cell lymphoma (TCL) is conventionally considered an aggressive disease, but some forms are histologically and clinically indolent. CD4 TCL is reported to be the most common subtype of TCL. We assessed flow cytometric characteristics, histologic features when available, and clinical outcomes of CD4+ TCL to determine if flow cytometry can be used to subclassify this group of lymphomas.

Objective

To test the hypothesis that canine CD4+ T‐cell lymphoma (TCL) is a homogeneous group of lymphomas with an aggressive clinical course.

Animals

Sixty‐seven dogs diagnosed with CD4+ TCL by flow cytometry and treated at 1 of 3 oncology referral clinics.

Methods

Retrospective multivariable analysis of outcome in canine CD4+ TCL including patient characteristics, treatment, and flow cytometric features.

Results

The majority of CD4+ TCL were CD45+, expressed low class II MHC, and exhibited an aggressive clinical course independent of treatment regimen (median survival, 159 days). Histologically, CD4+ TCL were classified as lymphoblastic or peripheral T cell. Size of the neoplastic lymphocytes had a modest effect on both PFI and survival in this group. A small number of CD4+ TCL were CD45− and class II MHC high, and exhibited an apparently more indolent clinical course (median survival not yet reached).

Conclusions and Clinical Importance

Although the majority of CD4+ TCL in dogs had uniform clinical and flow cytometric features and an aggressive clinical course, a subset had a unique immunophenotype that predicts significantly longer survival. This finding strengthens the utility of flow cytometry to aid in the stratification of canine lymphoma.

Detection of clonal antigen receptor gene rearrangement in dogs with lymphoma by real-time polymerase chain reaction and melting curve analysis

Background

Molecular techniques that detect canine lymphoma cells by their clonal antigen receptor gene rearrangement play an increasing role for diagnosis as well as for monitoring minimal residual disease during and after cytostatic therapy. However, the methods currently available are time-consuming and/or cost-intensive thus impeding the use in clinical routine. The aim of the present study was to develop and evaluate a real-time polymerase chain reaction (PCR) with subsequent melting curve analysis (MCA) for the detection of clonally rearranged antigen receptor genes in dogs with B and T cell lymphoma on non formalin-fixed and paraffin-embedded lymph node samples.

Results

In lymph node aspirates from 30 dogs with multicentric B cell lymphoma, real-time PCR with MCA detected clonal rearrangement in 100% and conventional PCR with polyacrylamide gel electrophoresis (PAGE) in 93% of samples. Both methods correctly identified clonality in 80% of lymph node aspirates of 10 dogs with T cell lymphoma. None of the two PCR systems detected clonal rearrangement in samples from 9 dogs with lymph node hyperplasia. Using a dilutional series with regular lymphoid desoxyribonucleic acid (DNA), detection limits of lymphoma DNA were as low as 0.8% and 6.25% for B and T cell clonal rearrangement with real-time PCR and MCA and at 3.13% and 12.5% with the conventional system. Median absolute detection limits of lymphoma DNA were shown to be at 0.1 ng and 1 ng for the B and T cell immunophenotype with the real-time PCR system and at 10 ng each with conventional PCR and PAGE.

Conclusions

Real-time PCR with MCA is a convenient and reliable method with a good analytical sensitivity. Thus, the method may assist the detection of clonal antigen receptor gene rearrangement in canine lymphoma patients in a clinical setting also in the presence of small amounts of neoplastic cells.

Application of flow cytometry in diagnosing lymphomas in dogs and cats

Classification of types of lymphomas is done by interpreting cell morphology results obtained in cytological and/or histological examinations. In recent years, additional methods like immunocytochemistry (ICC), immunohistochemistry (IHC), immunophenotyping by flow cytometry and polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR), have been used to diagnose and classify lymphomas. Unfortunately, none of these methods is completely specific and sensitive. Thus, a combination of several diagnostic methods or use of all available techniques allows for evaluation of morphological properties of cells like their maturity and diversification. Owing to the use of sets of antibodies it is possible to identify the phenotype of hyperplastic cells as well as their origin. Combination of results obtained through phenotypical analysis with flow cytometry examination with morphological, histological and genetic testing enables a detailed analysis of, in this case, lymphoproliferative diseases including reaction changes, primary and secondary immunological deficits as well as autoimmune diseases.

Making sense of lymphoma diagnostics in small animal patients

This article summarizes and compares the various assays available to aid in the diagnosis and characterization of lymphoma in small animal patients. These techniques include cytology, histopathology, immunocytochemistry and immunohistochemistry, immunophenotyping by flow cytometry, and polymerase chain reaction for clonal antigen receptor gene rearrangement.

Rapid, effective and user-friendly immunophenotyping of canine lymphoma using a personal flow cytometer

BACKGROUND

Widespread use of flow cytometry for immunophenotyping in clinical veterinary medicine is limited by cost and requirement for considerable laboratory space, staff time, and expertise. The Guava EasyCyte Plus (Guava Technologies, Hayward, CA, US) is the first, personal, bench-top flow cytometer designed to address these limitations.

OBJECTIVE

The aim of this study was to adapt the immunohistochemical protocol used for immunophenotyping of canine lymphoma to the personal flow cytometer for rapid, effective and user-friendly application to the diagnosis and prognosis of canine lymphoma and to demonstrate its practicality for widespread veterinary application. Performance of the personal flow cytometer for immunophenotyping T and B lymphocytes in blood and lymph nodes from normal dogs and dogs with lymphoproliferative disease, was assessed using only two monoclonal antibodies (against CD3 and CD21), and by comparison with analysis using two conventional flow cytometers.

METHODS

26 dogs with lymphoproliferative disease (23 with lymphoma, 3 with lymphocytic leukaemia) were studied along with 15 controls (2 non-lymphoma lymph nodes and 13 non-leukemic bloods. Lymphocytes were immunostained with fluorescent-labeled, monoclonal antibodies against CD3 and CD21. To assess the effectiveness of the personal flow cytometer in discrimination between T and B cell immunophenotypes, T and B cell counts for half the samples (14 blood and 11 lymph node) were also determined using the same method and conventional flow cytometers (FACSCalibur, Cyan Dako). To assess the effectiveness of the personal flow cytometer in discriminating between leukocyte types, lymphocyte differential counts were determined for 21 blood samples and compared with those from automated hematology analyzers (CELL-DYN 3500, n=11 and ADVIA 2120, n=10). Quality and sub-cellular distribution of immunostaining was assessed using fluorescence microscopy.

RESULTS

The protocol for immunophenotyping took 2 to 3 hours to complete from the point of receipt of sample to reporting of immunophenotype. The personal flow cytometer differential lymphocyte counts correlated highly (n=20; r=0.97, p<0.0001) with those of automated haematology analyzers. The personal flow cytometer counts consistently, but mildly, underestimated the percentages of lymphocytes in the samples (mean bias of -5.3%.). The personal flow cytometer immunophenotype counts were indistinguishable from those of conventional flow cytometers for both peripheral blood samples (n=13; r=0.95; p<0.0001; bias of -1.1%) and lymph node aspirates (n=11,r=0.98; p<0.001; bias of 1%). All but one leukemic and one lymphomatous lymph node sample, out of 26 samples of dogs with lymphoproliferative disease analyzed, could be immunophenotyped as either B or T cells.

CONCLUSIONS

We conclude that use of only 2 monoclonal antibodies is sufficient for immunophenotyping most cases of canine lymphoma by flow cytometry and enables rapid immunophenotyping. The personal flow cytometer may be as effectively used for immunophenotyping canine lymphoma as conventional flow cytometers. However, the personal flow cytometer is more accessible and user-friendly, and requires lower sample volumes.

Flow cytometric evaluation of peripheral blood and bone marrow and fine-needle aspirate samples from multiple sites in dogs with multicentric lymphoma

OBJECTIVE

To determine whether the extent of disease in dogs with lymphoma can be assessed via flow cytometry and to evaluate the suitability of fine-needle aspirates from the liver and spleen of dogs for flow cytometric examination.

ANIMALS

44 dogs with multicentric B-cell (n = 35) or T-cell lymphoma (9) and 5 healthy control dogs. Procedures-Peripheral blood and bone marrow samples and fine-needle aspirates of lymph node, liver, and spleen were examined via flow cytometry. Logarithmically transformed T-cell-to-B-cell percentage ratio (log[T:B]) values were calculated. Thresholds defined by use of log(T:B) values of samples from control dogs were used to determine extranodal lymphoma involvement in lymphoma-affected dogs; results were compared with cytologic findings.

RESULTS

12 of 245 (5%) samples (9 liver, 1 spleen, and 2 bone marrow) had insufficient cellularity for flow cytometric evaluation. Mean log(T:B) values of samples from dogs with B-cell lymphoma were significantly lower than those of samples from the same site in dogs with T-cell lymphoma and in control dogs. In dogs with T-cell lymphoma, the log(T:B) of lymph node, bone marrow, and spleen samples was significantly higher than in control dogs. Of 165 samples assessed for extranodal lymphoma involvement, 116 (70%) tested positive via flow cytometric analysis; results agreed with cytologic findings in 133 of 161 (83%) samples evaluated via both methods.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that flow cytometry may aid in detection of extranodal lymphoma involvement in dogs, but further research is needed. Most fine-needle aspirates of liver and spleen were suitable for flow cytometric evaluation.

High agreement of routine cytopathology and immunocytochemistry in canine lymphomas

The aim of this study was to compare the concordance of immunophenotype established with routine cytopathology (slides stained with Giemsa solution) and immunocytochemistry according to CD3 and CD79 alpha immunoreactivity. The study was performed on cytological samples of 70 canine lymphomas subtyped on the basis of the updated Kiel classification system. Additionally, cytologic samples were examined immunocytochemically for the CD3 and CD79 alpha antigens presence and thus immunophenotype of neoplastic growth was confirmed. The cytopathological and immunocytochemical diagnoses were then compared; in order to measure the concordance between immunocytochemistry (IC) result and Giemsa stain result of the same sample the Cohen's kappa coefficient was calculated. On the basis of the results of immunocytochemistry of 70 cases of canine lymphoma examined 42 were recognized as B cell lymphoma and 28 as T cell lymphoma. Full accordance between the results of routine cytopathology and IC was obtained in 63 out of 70 examined dogs (90% of cases). It can be concluded that cytopathological examination of Giemsa stained smears is helpful in determining the lymphoma cells immunophenotype. Additionally, it seems that combination of routine cytopathology and immunocytochemistry in cases of canine lymphomas allows to obtain the precise diagnosis in 90% of cases, and allows to receive most important information that is necessary for planning of appropriate therapy and to determine prognosis. Finally, this routine procedure allowed to eliminate the need of collection of tissue samples during surgery or core-biopsy and thus time, cost and patient discomfort related to more complex and invasive medical procedures can be easily reduced.

Practical aspects of immunocytochemistry in canine lymphomas

The aim of this study was to evaluate the utility of immunocytochemistry in a standard veterinary practice and to determine the immunophenotype of tumor cells in cases of multicentric lymphoma in dogs by immunocytochemical analysis of fine-needle biopsy specimens. The study was performed on cytological samples collected from 54 dogs, in which multicentric lymphoma was recognised based on clinical data, cytology or cytology and histology, and follow-up information. Diagnosis of lymphoma was established according to the updated Kiel classification. Immunocytochemical assays were conducted using commercially available antibodies to the pan T-lymphocyte marker CD3 and B cell antigen receptor complex CD79 alpha. Among all animals examined B cell lymphoma was recognized in 42/54 (77.8%) of cases, while in the remaining 12/54 (22.2%) of dogs T cell lymphoma was recognized. In 11 animals with lymphoma recognized cytologically, in which an entire lymph node was obtained for histology, the results of routine cytology and immunocytochemistry fully corresponded with findings revealed by histology and immunohistochemistry. Immunocytochemistry can be successfully conducted in smears stored at room temperature for 24 hours without changes of staining results. It can be stated that application of standard cytopathological assessment in connection with immunocytochemistry of lymph nodes samples collected from dogs with lymphoma is a method of choice for establishing final diagnosis, and avoids the need for reexamination or collection of tissue samples for histopathology and immunohistochemistry during surgical procedures in ambiguous cases.

Use of flow cytometric immunophenotyping to refine the cytological diagnosis of canine lymphoma

The diagnosis of canine lymphoma is a multi-step process involving clinical examination, diagnostic imaging, cytology, haematology, biochemical profiling, histopathology and ancillary techniques such as flow cytometry (FC). In human medicine, FC (in addition to cytology) is reported to increase the accuracy of diagnosis of most lymphoma sub-types. In dogs, FC can add a number of useful diagnostic features to the morphological evaluation of lymphoma including the evaluation of B or T cell lineage, antigen quantification and evaluation of aberrant patterns, the assessment of clonality, staging and the evaluation of minimal residual disease. In comparison to other immunophenotyping techniques, FC is rapid and easy to perform and 'gating' techniques can resolve mixed cell populations although the use of fresh samples is required and the appropriate equipment and its maintenance are quite expensive. The use of FC to refine cytological diagnosis could be further enhanced by the use of a multi-parametric approach and by the development of a wider panel of standardised canine-specific antibodies.

Hematologic abnormalities and flow cytometric immunophenotyping results in dogs with hematopoietic neoplasia: 210 cases (2002-2006)

BACKGROUND

Growing interest in veterinary oncohematology has facilitated the recent development and advancement of new techniques, such as flow cytometry, for immunophenotyping hematopoietic neoplasia in animals.

OBJECTIVE

The aim of this retrospective study was to characterize hematologic abnormalities and flow cytometric immunophenotyping (FCI) results in cases of hematopoietic neoplasia in dogs.

METHODS

Signalment, CBC data, and FCI results were obtained for 210 dogs with blood samples submitted to our laboratory. Immunophenotyping was carried out using an Epics XL-MCL flow cytometer and a panel of 10 antibodies (CD45, CD3, CD4, CD8, CD79, CD21, CD14, CD34, CD41/61, CD61). The prevalence and severity of hematologic abnormalities was determined for the different types of hematopoietic neoplasms.

RESULTS

Based on cell morphology and phenotype, cases were classified as: acute lymphoblastic leukemia (ALL, n=51), acute myeloid leukemia (AML, n=33), chronic lymphocytic leukemia (CLL, n=61), and leukemic high-grade lymphoma (L-HGL, n=65). Most cases of ALL (47/51) and L-HGL (41/65) had a B-cell phenotype, while most cases of CLL (54/61) had a T-cell phenotype, with a high prevalence of the large granular lymphocyte subtype (49/61). Anemia was found in 85% of all cases and was significantly more severe in ALL and AML compared with CLL and L-HGL. Neutropenia was seen in 64-78% of acute leukemias (AML and ALL) in contrast to no cases of CLL and 11% of L-HGL. Thrombocytopenia was seen in 88-90% of acute leukemias in contrast to 15% of CLL and 40% of L-HGL. Thrombocytopenia was more prevalent (71% vs 22%) and significantly more severe in T-cell vs B-cell L-HGL.

CONCLUSION

A standard CBC is useful in suggesting the type of hemoproliferative disorder and may also help to predict the phenotype, especially in cases of L-HGL.

Immunophenotypic and cytomorphologic subclassification of T-cell lymphoma in the boxer breed

The boxer breed is at high risk for developing lymphoma and, in contrast to the general canine population, is predisposed to the T-cell variant of the disease. The purpose of this study was to more accurately classify lymphoma in this breed. Clinical, cytomorphologic and immunophenotypic data were examined in 43 boxers with lymphoma. Twenty-five cases were collected prospectively and a further 18 cases were obtained retrospectively. Lymphomas were classified as multicentric (n=29), mediastinal (n=6) and intestinal (n=8). Of the 40 immunophenotyped samples, 34 (85%) were T-cell, 5 (12.5%) were B-cell and 1 was a non-B-cell non-T-cell lymphoma. Immunophenotypic subtyping was done on prospectively collected T-cell lymphoma samples (n=22) to differentiate CD4 (helper) from CD8 (cytotoxic) T-cell origin as well as to determine the T-cell receptor (TCR) expression (TCRalphabeta vs. TCRdeltagamma). Phenotypic expression was CD4+ (n=12), double negative (DN) (n=6), double positive (DP) (n=1) and CD8+ (n=1), respectively, while two samples had no interpretable result. 20/22 samples were TCRalphabeta+ with only 1 sample being TCRdeltagamma+ and 1 with no interpretable result. Cytomorphologic analysis was done on the same 22 samples using the World Health Organization (WHO) classification scheme. According to this scheme, 17/22 samples were classified as lymphoblastic, 2/22 as large cell peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS), 2/22 as large granular lymphoma (LGL) high-grade and 1/22 as small lymphocytic. The results of this study indicate that lymphoma in the boxer breed is a disease comprised predominantly of TCRalphabeta+, CD4+ (helper) T-cells with lymphoblastic (high-grade) morphology.