Prognostic variables in canine multicentric lymphosarcoma

Mitotic activity: A systematic literature review of the assessment methodology and prognostic value in canine tumors

One of the most relevant prognostic indices for tumors is cellular proliferation, which is most commonly measured by the mitotic activity in routine tumor sections. The goal of this systematic review was to analyze the methods and prognostic relevance of histologically measuring mitotic activity that have been reported for canine tumors in the literature. A total of 137 articles that correlated the mitotic activity in canine tumors with patient outcome were identified through a systematic (PubMed and Scopus) and nonsystematic (Google Scholar) literature search and eligibility screening process. Mitotic activity methods encompassed the mitotic count (MC, number of mitotic figures per tumor area) in 126 studies, presumably the MC (method not specified) in 6 studies, and the mitotic index (MI, number of mitotic figures per number of tumor cells) in 5 studies. A particularly high risk of bias was identified based on the available details of the MC methods and statistical analyses, which often did not quantify the prognostic discriminative ability of the MC and only reported P values. A significant association of the MC with survival was found in 72 of 109 (66%) studies. However, survival was evaluated by at least 3 studies in only 7 tumor types/groups, of which a prognostic relevance is apparent for mast cell tumors of the skin, cutaneous melanoma, and soft tissue tumor of the skin and subcutis. None of the studies using the MI found a prognostic relevance. This review highlights the need for more studies with standardized methods and appropriate analysis of the discriminative ability to prove the prognostic value of the MC and MI in various tumor types. Future studies are needed to evaluate the influence of the performance of individual pathologists on the appropriateness of prognostic thresholds and investigate methods to improve interobserver reproducibility.

Prognostic role of the updated Kiel classification in canine high-grade T-cell lymphomas

BACKGROUND

The aim of this study was to determine and describe the prognostic role of the morphological subtype determined according to the updated Kiel classification in dogs with high-grade T-cell lymphomas (HGTCLs) depending on the treatment applied.

OBJECTIVES

The HGTCLs were classified into three subtypes according to the updated Kiel classification: pleomorphic mixed (PM), lymphoblastic lymphoma/acute lymphoblastic leukaemia and plasmacytoid (P). The treatment was divided into a palliative therapy (PlT) group and a chemotherapy (ChT) group.

METHODS

The study was conducted between 2009 and 2017, and it enrolled 58 dogs in which cytomorphological and immunocytochemistry diagnoses were HGTCL.

RESULTS

Overall survival (OS) was significantly longer in the ChT group (median OS-4 months, interquartile range [IQR] from 2 to 8 months) than in the PlT group (median OS-6 weeks, IQR from 1 week to 3 months). In the PlT group, PM subtype and glucocorticosteroids (GCSs) treatment proved significantly and independently linked to longer OS and approximately three-fold lower risk of death during the study period (adjusted hazard ratio [HRadj] = 0.26, confidence interval [CI] 95%: 0.08-0.81; p = 0.020 and HRadj = 0.30, CI 95%: 0.11-0.77; p = 0.013, respectively), although due to small group size, precision of estimations was poor (wide CI 95%). In the ChT group, >7 days elapsing between diagnosis and the beginning of chemotherapy and GCS treatment prior to chemotherapy were significantly associated with lower chance of complete remission (CR; p = 0.034 for both); GCS treatment prior to chemotherapy was significantly associated with shorter OS (p = 0.016); chemotherapy based on the modified CHOP protocol was significantly associated with higher chance of CR (p = 0.034) and longer OS (p = 0.039); and CR was significantly linked to longer OS (p = 0.001).

CLINICAL SIGNIFICANCE

The morphological subtype of HGTCL has some prognostic value in dogs treated palliatively (with PM subtype associated with longer OS than P subtype); however, this effect is no longer visible when a dog is treated with chemotherapy.

Use of Lomustine and Prednisolone as First-Line Treatment in Canine Multicentric Lymphoma

Multiagent chemotherapy is considered the most effective treatment for canine high-grade lymphoma; however, due to cost and time requirements, single-agent protocols have also been described. The aim of our study was to evaluate the outcome and prognostic factors of dogs affected by multicentric lymphoma treated with lomustine and prednisolone as first-line treatment. Cases of medium-large-cell multicentric lymphoma treated with lomustine and prednisolone were included in the study. Response to therapy, time to progression (TTP), median disease-free interval (MDFI) and median survival time (MST) were retrospectively described. Thirty cases were included. Eleven (36.67%) were T cell, 11 (36.67%) were B cell and 8 (26.66%) had unknown immunophenotype. The overall response rate (RR) was 87%, with 15 patients achieving CR (50%) and 11 patients PR (37%). The median TTP, MDFI and MST were 42, 63 and 90 days, respectively. The only factor significantly associated with MDFI and MST was the stage. Dogs with multicentric lymphoma treated with lomustine and prednisolone have lower RR, TTP, MDFI and MST compared with dogs receiving multiagent protocols. Based on the short-lasting response, this study confirms that this protocol might have minimal utility beyond palliation.

T-cell lymphoma involving the rectum of a dog

A mediastinal mass was diagnosed in a 7-year-4-month-old neutered female mixed breed dog following a 3-week history of lethargy, hyporexia and pyrexia. Bi-cavitary imaging, needle aspirate cytology and flow cytometry confirmed WHO clinical stage IVb, intermediate to large T-cell lymphoma involving the mediastinum, liver and spleen. The dog initially responded to a multidrug chemotherapy protocol but clinical deterioration occurred 3 months later. The dog presented with anorexia, vomiting and diarrhoea, associated with marked faecal tenesmus and haematochezia, initially believed by the primary care practitioner to be related to chemotherapy toxicity. However, rectal examination revealed multiple sessile and pedunculated masses. Further diagnostic imaging, cytology and flow cytometry confirmed progressive disease, including T-cell lymphoma of the rectum. Histology and immunohistochemistry confirmed an infiltrate of intermediate-sized CD3-positive neoplastic cells that expanded the rectal mucosa. Rectal lymphoma is uncommon in dogs and previous cases have been B cell in origin. In this report we describe the clinical presentation and macro- and microscopic findings of a case of canine T-cell lymphoma involving the rectum.

Procarbazine, prednisolone and cyclophosphamide (PPC) oral combination chemotherapy protocol for canine lymphoma

Orally administered daily chemotherapy offers a novel treatment approach for canine lymphoma in a population of dogs that have failed or not tolerated maximum tolerable dose chemotherapy. A multidrug oral chemotherapy protocol was designed and implemented for the treatment of fifty dogs with multicentric lymphoma with minimal side effects. The protocol consisted of oral procarbazine, prednisolone and cyclophosphamide (PPC) administered daily. Efficacy and toxicity were evaluated by clinical and laboratory evaluation. An overall response rate of 70% was achieved, with 24% and 46% of dogs having a partial and complete response, respectively, to treatment with the PPC protocol. Response to the PPC protocol (complete or partial) and age were the only factors identified as prognostic for time from initiation of the PPC chemotherapy until death. Overall, the protocol was very well tolerated with only one dog requiring protocol discontinuation due to grade 4 thrombocytopenia. Eight dogs recorded gastrointestinal toxicities, seven grade I and one grade II toxicity. These findings demonstrate that the administration of a continuous oral combination chemotherapy can provide comparable survival times in the rescue setting in dogs with multicentric lymphoma with minimal side effects.

Flow Cytometric Assessment of Ki-67 Expression in Lymphocytes From Physiologic Lymph Nodes, Lymphoma Cell Populations and Remnant Normal Cell Populations From Lymphomatous Lymph Nodes

Recent literature suggests conventional flow cytometric (FCM) immunophenotyping complemented by Ki-67 FCM assessment as a reliable tool to classify canine lymphomas. Ki-67 expression assessed by FCM is rarely reported in canine lymphoma cases and reference data for normal canine lymph nodes are missing. Moreover, nothing is known about the Ki-67 expression within the occasionally observed remnant cell population within the gates of normal lymphocytes in lymphoma cases. Aim of this study was to compare flow cytometric Ki-67 expression of lymphocyte populations from normal canine lymph nodes, lymphoma cells from World-Health-Organisation (WHO) classified lymphoma patient samples and their neighboring normal remnant cell population. Cryopreserved lymphocyte cell suspensions from normal lymph nodes from eight dogs free of lymphoma served as reference material. Fourteen cases diagnosed by cytology, FCM, clonality testing, histopathology including immunohistochemistry consisting of 10 DLBCL, 1 MZL, 1 PTCL and 2 TZL showed a residual small lymphocyte population and were investigated. The Ki-67 expression in normal canine lymphoid tissue was 3.19 ± 2.17%. Mean Ki-67 expression in the malignant cell populations was 41 ± 24.36%. Ki-67 positivity was 12.34 ± 10.68% in the residual physiologic lymphocyte population, which otherwise exhibited a physiologic immunophenotype pattern. This ratio was equivalent (n = 3) or lower (n = 11) than the Ki-67 expression of the malignant cell population within the sample. This is the first report of FCM derived Ki-67 expression combined with immunophenotype patterns in normal canine lymph nodes, compared with lymphoma cell populations and residual normal cell populations of lymphoma cases diagnosed by state of the art technology.

Peripheral blood cell ratios as prognostic factors in canine diffuse large B-cell lymphoma treated with CHOP protocol

Diffuse large B-cell lymphoma (DLBCL) is the most common haematopoietic tumour in dogs and recognized as clinical model for its human counterpart. Recently, neutrophil-to-lymphocyte (NLR) and lymphocyte-to-monocyte (LMR) ratios have been shown to predict time-to-progression (TTP) and lymphoma-specific survival (LSS) in dogs with DLBCL treated with CHOP-based chemotherapy. We retrospectively evaluated in 59 dogs diagnosed with DLBCL the prognostic value of haematological parameters and derived ratios: NLR, LMR, platelet-to-lymphocyte (PLR) and platelet-to-neutrophil (PNR) ratios for TTP, LSS and associated secondary end-points (time-to-progression-rate [TTPR] and lymphoma-specific survival-rate [LSSR]) as rates at 180 and 365 days. PNR is an independent prognostic marker (p ≤ .001) for TTPR/180 and 365 days, dogs with a PNR above 0.032 were more likely to progress before 180 days (sensitivity 46.5%, specificity 87.5%, p = .004). On univariate analysis, NLR showed a prognostic significance for LSSR/180 (p = .006) and LSSR/365 (p = .009). A baseline NLR value below 7.45 was positively associated with survival at 180 days (sensitivity 52%, specificity 85.3%, p = .025). The presence of substage b, was associated with early progression and decreased survival at 180 days (p = .031). Anaemia significantly reduced LSSR at 365 days (p = .028). This is the first study evaluating PLR and PNR in canine DLBCL and demonstrates that PNR could be a predictor of early lymphoma progression. Since peripheral blood cell composition can be affected by several non-oncological causes, the development of larger multicenter studies with homogeneous inclusion criteria could help to better determine the true predictive values of blood cell ratios in dogs' DLBCL treated with CHOP chemotherapy.

Clinicopathological characteristics and prognostic factors for canine multicentric non-indolent T-cell lymphoma: 107 cases

Canine lymphoma, as the most common haematopoietic malignancy, encompasses a group of heterogeneous diseases and even within the T-cell immunophenotype, differences in clinical presentation and responses to treatment exist. The aim of this retrospective study was to determine outcomes and prognostic factors of 107 dogs with multicentric non-indolent T-cell lymphoma (TCL) receiving lomustine-based (70%) and non-lomustine-based (30%) treatment. The majority were Labradors, Boxers, mixed-breed dogs and Dogue de Bordeaux. Eighty-six percent were substage b, 77% had mediastinal involvement, 15% had suspected bone marrow involvement and 12% had other extra-nodal sites of disease. The overall response rate to induction therapy was 80%; dogs receiving procarbazine in the induction protocol (P = .042), dogs with neutrophil concentration below 8.7 × 10e⁹ /L (P = .006) and mitotic rate below 10 per 5 high power field (P = .013), had greater response rates. Median progression-free survival (PFS) for the first remission was 105 days; lack of expression of CD3 on flow cytometry (P < .0001) and pretreatment with steroid (P = .012) were significantly associated with shorter PFS. Median overall survival time (OST) was 136 days; co-expression of CD79a (P = .002), lack of CD3 expression on flow cytometry, presence of anaemia (P = .007), and monocytopenia (P = .002) were predictive of shorter OST. Multicentric non-indolent TCL in dogs is an aggressive cancer with new possible prognostic factors.

Significant advances in veterinary oncology - 60 years on

The first edition of the Journal of Small Animal Practice published in February 1960, contained a paper entitled "Recent Treatments of Malignant Neoplasia" by Dr Larry Owen. Now we have reached the 60th anniversary of JSAP, that article provides a baseline from which to review subsequent advances in veterinary oncology, which now includes worldwide networks that have resulted in veterinary oncology becoming the multidisciplinary speciality that it is today. There certainly have been many advances in understanding of the pathology and epidemiology of animal cancers and in methods of diagnosis and treatment. However, the subject has become so large and diverse that not all aspects can be covered in detail here. It should also be acknowledged that there are still many gaps in knowledge in this field and that, because of a lack of randomised clinical trials, the evidence base for what is often regarded as "standard of care" is weak.

Incidence and risk factors for the diagnosis of lymphoma in dogs in UK primary-care practice

OBJECTIVES

To identify the incidence, risk factors and presenting signs of lymphoma in dogs presenting to primary-care practice in the UK using analysis of data within the VetCompass™ programme.

MATERIALS AND METHODS

Case records from the VetCompass™ programme from primary-care practices in the UK were searched for newly diagnosed lymphoma in dogs within a 1-year period: 2013. Diagnosis was based on clinical records with or without laboratory confirmation. Signalment was evaluated as risk factors for lymphoma diagnosis using multivariable logistic regression.

RESULTS

There were 286 presumed newly diagnosed cases identified during 2013 from 455,553 dogs (overall incidence risk 63 of 100,000 dogs per year) of which 193 (67%) were laboratory confirmed (42 of 100,000 dogs per year). Advanced age, dogs older than 12 years, dogs weighing more than 30 kg and some specific breeds were significantly associated with lymphoma diagnosis. Only 18 dogs (6%) of the population identified were referred to a specialist clinic.

CLINICAL SIGNIFICANCE

This study concurs with others that age, bodyweight and breed are significant risk factors for lymphoma. Results of this study highlight: (1) the low number of dogs with lymphoma that are referred to specialists in the UK and (2) that few dogs undergo immunophenotyping (which can carry prognostic importance), emphasising the importance of epidemiological programmes that evaluate diseases presented to primary-care veterinarians.

Evaluation of serum thymidine kinase 1 activity as a biomarker for treatment effectiveness and prediction of relapse in dogs with non-Hodgkin lymphoma

BACKGROUND

Serum thymidine kinase 1 (sTK1) activity is closely correlated with DNA synthesis.

OBJECTIVES

Evaluate sTK1 activity as a biomarker for treatment response and early detection of relapse in dogs with lymphoma.

ANIMALS

Ninety-seven client-owned dogs with naive or relapsed lymphoma and 23 healthy dogs.

METHODS

Prospective study. Serum TK1 activity measured by refined ELISA-based method (DiviTum assay, Biovica International) before treatment, at clinical response, and every 4 weeks until relapse or last follow-up.

RESULTS

Serum TK1 activity was ≤20 Du/L in 96% (22/23) of healthy dogs. Pretreatment sTK1 activity was >20 Du/L in 88% (85/97) dogs with lymphoma. At clinical response, sTK1 activity was significantly lower in dogs with complete (CR, n = 36) versus partial (PR, n = 29) response (P < .0001). Sensitivity (Se) and specificity (Sp) of sTK1 activity for detecting nonfully responders were 76% and 100%, respectively, with cutoff of 119.5 Du/L (AUC, 0.90; 95%-CI, 0.81-0.98; P < .0001). In dogs with CR, a 5-fold increase in sTK1 activity at a 4-week interval predicted relapse at the subsequent 4-week assessment with a Se 50% and Sp 94% (AUC, 0.72; 95%-CI, 0.55-0.90; P = .02). An increase of sTK1 activity (>2.7-fold value measured at clinical response) predicted relapse at subsequent 4-week assessment with a Se 61% and Sp 88% (AUC, 0.79; 95%-CI, 0.64-0.95; P = .004).

CONCLUSIONS AND CLINICAL IMPORTANCE

Monitoring sTK1 activity could help to detect complete responders and early disease progression in dogs with lymphoma.

Prognostic significance of Ki67 and its correlation with mitotic index in dogs with diffuse large B-cell lymphoma treated with 19-week CHOP-based protocol

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma in dogs. We evaluated Ki67 immunoexpression and mitotic index (MI) in dogs diagnosed with DLBCL and treated with a 19-wk CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) protocol. Twenty-nine lymph node samples from dogs diagnosed with DLBCL were analyzed for Ki67 immunostaining, and positive cells present in 1 cm² were counted in a grid reticle for comparison of survival times above and below the means. The Ki67 mean was 107, and the MI mean was 21. There was a significant ( p < 0.05) difference in median survival time between Ki67 immunostaining above and below the mean, with no difference in MI groups. Ki67 values >107 positive cells per 5 HPF counted in a grid reticle were associated with shorter survival times in dogs with DLBCL treated with a 19-wk CHOP-based protocol.

Retrospective analysis of factors affecting clinical outcome following CHOP-based chemotherapy in dogs with primary nodal diffuse large B-cell lymphoma

Numerous factors are known to affect the prognosis of dogs with chemotherapy-treated lymphomas. However, prognostic factors for dogs with specific subtypes of lymphoma are less clearly defined. The objective of this study was to identify prognostic factors for dogs receiving CHOP-based chemotherapy for primary nodal diffuse large B-cell lymphoma (DLBCL). Medical records of dogs treated for DLBCL at the Purdue Veterinary Teaching Hospital (PUVTH) from 2006 to 2016 were reviewed. Factors potentially related to prognosis were analysed using multivariable statistical methods. Ninety-eight dogs were included in the study. Best overall response to chemotherapy was complete remission in 80 dogs (81.6%) and partial remission in 18 dogs (18.4%). Median progression-free survival (PFS) for the entire population was 252 days (range 19-1068). Factors significantly associated with achieving partial (rather than complete) remission following CHOP included presence of thrombocytopenia at diagnosis (OR 6.88; 95% CI 1.98-23.93; P = .002), baseline serum globulin concentration (OR 2.63; 95% CI 1.03-6.75; P = .044), and age at diagnosis (OR 1.36; 95% CI 1.08-1.71; P = .009). Factors significantly associated with PFS in the lowest quartile (≤93 days) included presence of thrombocytopenia at diagnosis (OR 8.72; 95% CI 1.54-49.33; P = .014), age at diagnosis (OR 1.47; 95% CI 1.12-1.94; P = .005), and baseline neutrophil count (OR 1.18; 95% CI 1.02-1.37; P = .025). Presence of thrombocytopenia, greater age, higher neutrophil count, and higher serum globulin concentration all may be associated with a particularly poor outcome in dogs receiving CHOP-based chemotherapy for DLBCL.

Canine acute leukaemia: 50 cases (1989-2014)

Acute leukaemia (AL) is a bone marrow malignancy of hematopoietic progenitors that historically is poorly responsive to treatment. With the widespread adoption of dose-intense chemotherapy, more human patients attain long-term survivals, but whether comparable progress has been made in canine AL is unknown. To investigate this question, medical records from three academic veterinary hospitals were reviewed. Fifty dogs met the criteria for AL, having excess circulating or marrow blasts, a major cytopenia(s), and no substantial lymphadenopathy. Thirty-six dogs received cytotoxic chemotherapy; 23 achieved a complete or partial response for a median of 56 days (range, 9-218). With failure or relapse, 14 dogs were rescued. Median survival with treatment was poor at 55 days (range, 1-300). Untreated (n = 6) and palliatively-treated (n = 8) dogs lived a median of 7.5 days. Most dogs developed chemoresistance within weeks of initiating treatment, and consequently, survival times for AL remain disappointingly short.

Canine Indolent Nodular Lymphoma

Sixty-six cases of indolent canine lymphoid proliferation were reviewed. Age ranged from 1.5 to 16 years (median 9.0 years). Dogs of 26 breeds, plus 13 of mixed breeding or unknown lineage, were represented. B-Cell lymphomas (CD79a+) predominated. Marginal zone lymphoma (MZL), the largest group, involved lymph node (33 cases) and spleen (13 cases), with both tissues involved in five of these cases. Follicular lymphoma (FL) involved lymph nodes (five cases), and mantle cell lymphoma (MCL) occurred as solitary splenic masses (three cases). Nodal CD3+ T-zone lymphomas (TZL) (10 cases), were included since they resembled late-stage MZL at the architectural level. Two cases of marginal zone hyperplasia (MZH) were included to aid in differentiation of early MZL. Clonality status was determined in 54 cases by analysis of immunoglobulin heavy chain (IGH) and T-cell antigen receptor gamma (TCRG) gene rearrangement. Clonal rearrangement of IGH was detected in 28 of 35 MZL cases (80%), four of four FL cases (100%) and three of three MCL cases (100%). Concurrent cross lineage rearrangement of TCRG was detected in six MZL and two FL cases. Clonal rearrangement of TCRG was documented in five of eight TZL cases (63%). Limited survival data obtained for 18 dogs indicated that the B-cell lymphomas (MZL, MCL, and FL) and the T-cell lymphoma (TZL) were associated with indolent behavior and long survival. Although to the authors' knowledge, the true incidence of canine indolent lymphomas is unknown, the tumors are not rare and may have been underrecognized. Recognition of their architectural features, routine application of immunophenotyping, and molecular clonality assessment should alleviate this.

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

Fifty canine lymphomas were classified cytomorphologically using the updated Kiel classification scheme. Aspirates of lymph nodes from dogs with lymphoma were stained using 5 canine-specific antibodies and 3 human-specific antibodies that cross-react with canine lymphocytes. The antibody-stained aspirates were analyzed by flow cytometry. A total of 32 (64%) of the 50 lymphomas were characterized as B-cell origin and 18 (36%) were of T-cell origin. B-cell lymphomas were identified in 12 females and 20 males with a mean age of 8.35 years. T-cell lymphomas were identified in 8 females and 10 males with a mean age of 7.9 years. A minority of the lymphomas were low-grade B-cell and T-cell lymphomas (6/50, 12% and 4/50, 8%, respectively). The most common morphologic types were high-grade centroblastic and unclassifiable plasmacytoid for B- and T-cell lymphomas (18/50, 36% and 7/50, 14%, respectively).

[Multicentric lymphoma in 411 dogs - an epidemiological study]

OBJECTIVE

To provide an overview of the epidemiology of canine multicentric lymphoma in Germany.

MATERIAL AND METHODS

A total of 411 dogs with multicentric malignant lymphoma were retrospectively analysed regarding breed, age, sex, weight and the number of animals dogs with hypercalcaemic lymphoma and B-/T-immunophenotype, and compared to two reference populations (total own clinic population, n   =   52  142; dogs with health insurance in Germany, n   =   123  423).

RESULTS

In total, 298 (72.5%) of the 411 dogs belonged to 86 different breeds, while 113 (27.5%) dogs were mixed breed. In comparison to both reference populations, a breed predisposition for the American Pitbull Terrier (odds ratio [OR] 5.2 and 18.5), American Staffordshire Terrier (OR 3.3 and 4.6), Briard (OR 5.6 and 9.5), Bullmastiff (OR 7.8 and 5.0), Irish Setter (OR 3.3 and 4.1) and Rottweiler (OR 2.8 and 3.6) was found. Golden Retrievers (n = 22, OR 1.3 and 0.9) and Bernese Mountain Dogs (n = 22, OR 2.4 and 2.0) were frequently affected in absolute numbers, but when compared to the reference populations an OR < 3 was detected. Mean body weight was 30.2 ± 13.7 kg; only 75 (18%) dogs weighed < 15 kg. Amongst the small dogs (< 15 kg), there was a large number of West Highland White Terriers (n = 12). Mean age of the dogs with lymphoma was 7.9 ± 2.7 years. Dogs weighing ≥ 15 kg were significantly (p < 0.001) younger (7.6 ± 2.4 years) compared to dogs weighing < 15 kg (9.3 ± 3.2 years). Dogs with a B-cell immunophenotype (8.5 ± 2.6 years) were significantly older compared to dogs with a T-cell immunophenotype (6.4 ± 1.8 years) (p < 0.001). There was no gender predisposition (54% male, 46% female). Hypercalcaemia as an indicator of T-cell lymphoma was present in 44 (11.4%) of the dogs. A T-cell and B-cell immunophenotype was found in 20.6% and 79.4% of the dogs, respectively.

CLINICAL RELEVANCE

This study confirms previous data about breed predispositions for canine malignant multicentric lymphoma and demonstrates that further breeds are predisposed (Briard, West Highland White Terrier, Irish Setter). Small-breed dogs (< 15 kg BM) appear to be affected with lymphoma at a greater age.

Prognostic significance of Ki67 evaluated by flow cytometry in dogs with high-grade B-cell lymphoma

Ki67 can discriminate between high- and low-grade canine lymphomas, but its prognostic role in specific subtypes of the neoplasm is unknown. We assessed the prognostic significance of Ki67% (percentage of Ki67-positive cells), evaluated by flow cytometry, in 40 dogs with high-grade B-cell lymphoma, treated with a modified Wisconsin-Madison protocol (UW-25). The following variables were investigated for association with lymphoma specific survival (LSS) and relapse free interval (RFI): Ki67%, breed, sex, age, stage, substage, complete remission (CR). By multivariate analysis, Ki67% (P = 0.009) and achievement of CR (P = 0.001) were independent prognostic factors for LSS. Dogs with intermediate Ki67% (20.1-40%) presented longer LSS and RFI (median = 866 and 428 days, respectively) than dogs with low (median = 42 days, P < 0.001; median = 159 days, P = 0.014) or high (median = 173 days, P = 0.038; median = 100 days, P = 0.126) values. Determination of Ki67 is a prognostic tool that improves the clinical usefulness of flow cytometric analysis in canine high-grade B-cell lymphoma.

Exome sequencing of lymphomas from three dog breeds reveals somatic mutation patterns reflecting genetic background

Lymphoma is the most common hematological malignancy in developed countries. Outcome is strongly determined by molecular subtype, reflecting a need for new and improved treatment options. Dogs spontaneously develop lymphoma, and the predisposition of certain breeds indicates genetic risk factors. Using the dog breed structure, we selected three lymphoma predisposed breeds developing primarily T-cell (boxer), primarily B-cell (cocker spaniel), and with equal distribution of B- and T-cell lymphoma (golden retriever), respectively. We investigated the somatic mutations in B- and T-cell lymphomas from these breeds by exome sequencing of tumor and normal pairs. Strong similarities were evident between B-cell lymphomas from golden retrievers and cocker spaniels, with recurrent mutations in TRAF3-MAP3K14 (28% of all cases), FBXW7 (25%), and POT1 (17%). The FBXW7 mutations recurrently occur in a specific codon; the corresponding codon is recurrently mutated in human cancer. In contrast, T-cell lymphomas from the predisposed breeds, boxers and golden retrievers, show little overlap in their mutation pattern, sharing only one of their 15 most recurrently mutated genes. Boxers, which develop aggressive T-cell lymphomas, are typically mutated in the PTEN-mTOR pathway. T-cell lymphomas in golden retrievers are often less aggressive, and their tumors typically showed mutations in genes involved in cellular metabolism. We identify genes with known involvement in human lymphoma and leukemia, genes implicated in other human cancers, as well as novel genes that could allow new therapeutic options.

Outcome and Prognostic Factors for Canine Splenic Lymphoma Treated by Splenectomy (1995-2011)

OBJECTIVE

To assess the outcome of canine splenic lymphoma treated with splenectomy and to evaluate prognostic factors, including involvement of other sites, adjuvant chemotherapy, and the effect of World Health Organization (WHO) histological classification of canine malignant lymphoma.

DESIGN

Multi-institutional, retrospective study.

ANIMALS

Client-owned dogs (n = 28).

METHODS

Medical records (1995-2011) of dogs with a histological diagnosis of splenic lymphoma and treated by splenectomy submitted by Veterinary Society of Surgical Oncology members were reviewed. Included were dogs treated with or without adjuvant therapy. Overall survival, disease-free interval, and cause of death were determined. Prognostic factors and the WHO histological classification of canine malignant lymphoma were evaluated with respect to outcome.

RESULTS

Dogs with splenic lymphoma treated by splenectomy had a 1-year survival rate of 58.8%, after which no animals died of their disease. B cell lymphoma held a better prognosis for survival than other variants of splenic lymphoma. Marginal zone lymphoma and mantle cell lymphoma were the most common B cell lymphoma subtypes in our study. Hemoabdomen and clinical signs related to splenic lymphoma, including abdominal distention, lethargy, and anorexia, were poor prognostic indicators, whereas disease confined to the spleen was a positive prognostic indicator. Pre- or postoperative adjuvant chemotherapy did not provide a survival benefit.

CONCLUSION

Based on our sample population, splenectomy alone was an effective treatment for splenic lymphoma in cases with disease confined to the spleen. Chemotherapy may not improve survival in cases of lymphoma restricted to the spleen.

The animal-dependent risk factors in canine T-cell lymphomas

Malignant lymphomas are one of the most common malignancies occurring in dogs; among them T-cell tumours are less commonly recognized. Recently, many authors have recommended cytology as a sufficient diagnostic method for canine lymphomas, especially if supported by immunocytochemistry or flow cytometry. The aim of the study was to characterize animal-dependent risk factors in canine T-cell lymphomas (TCLs) in Poland, including specific cytological subtypes. Determination of the type and subtype of the tumour was made based on the updated Kiel cytological classification adopted for dogs as previously described. Two breeds turned out predisposed to TCL (dog de Bordeaux and Boxer) while no predisposition to B-cell lymphoma could be evidenced. Dogs with low-grade lymphoma were significantly older than those with high-grade lymphoma.

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.

Comparative study of histopathology and immunohistochemistry of indefinite round cell cutaneous tumors and characterization of canine lymphoma

With the purpose of shedding light on some doubts in veterinary oncology, the present article intends to compare the results of histopathological and immunohistochemical examinations of unspecific round cell neoplasia, to realize immunophenotyping of canine lymphoma cases, to establish the T or B origin of neoplastic cells, and to determine the degree of proliferation and apoptosis of lymphomas by immunohistochemistry. Of 11 animals presenting immunohistochemical diagnosis of lymphoma, five had been diagnosed as Lymphoma by HE staining of histopathological slides and six had been classified as unspecific round cell neoplasia. All cases submitted to immunohistochemical examination were T-cell lymphomas. There was a positive correlation between cell proliferation and apoptosis. The comparison among histopathological and immunohistochemical results obtained in the cases examined in the present study suggested that immunohistochemistry is essential for the differentiation of round cell neoplasia.

Dissecting the regulatory microenvironment of a large animal model of non-Hodgkin lymphoma: evidence of a negative prognostic impact of FOXP3+ T cells in canine B cell lymphoma

The cancer microenvironment plays a pivotal role in oncogenesis, containing a number of regulatory cells that attenuate the anti-neoplastic immune response. While the negative prognostic impact of regulatory T cells (Tregs) in the context of most solid tissue tumors is well established, their role in lymphoid malignancies remains unclear. T cells expressing FOXP3 and Helios were documented in the fine needle aspirates of affected lymph nodes of dogs with spontaneous multicentric B cell lymphoma (BCL), proposed to be a model for human non-Hodgkin lymphoma. Multivariable analysis revealed that the frequency of lymph node FOXP3⁺ T cells was an independent negative prognostic factor, impacting both progression-free survival (hazard ratio 1.10; p = 0.01) and overall survival (hazard ratio 1.61; p = 0.01) when comparing dogs showing higher than the median FOXP3 expression with those showing the median value of FOXP3 expression or less. Taken together, these data suggest the existence of a population of Tregs operational in canine multicentric BCL that resembles thymic Tregs, which we speculate are co-opted by the tumor from the periphery. We suggest that canine multicentric BCL represents a robust large animal model of human diffuse large BCL, showing clinical, cytological and immunophenotypic similarities with the disease in man, allowing comparative studies of immunoregulatory mechanisms.

Flow cytometric evaluation of ki67 for the determination of malignancy grade in canine lymphoma

Ki67 is a nuclear antigen significantly correlated with degree of malignancy in human non-Hodgkin lymphomas. We wanted to assess the ability of flow cytometric evaluation of Ki67 index (Ki67I) in differentiating the grade of malignancy in canine lymphomas. Ki67I was determined on lymph node aspirates of 90 immunophenotyped lymphomas classified according to the updated Kiel classification: 80 high grade (HG, 62 B cell and 18 T cell) and 10 low grade (LG, 3 B cell and 7 T cell) lymphomas. HG lymphomas showed significantly higher Ki67I compared with LG lymphomas (P < 0.0001). A significant difference in HG lymphomas was detected between B- and T-immunophenotypes. Receiver operating characteristic (ROC) curve highlighted a high accuracy of Ki67I in recognizing HG lymphomas [area under the curve (AUC) = 99.4] and a cut-off value of 12.2% was established (sensitivity = 96.3% and specificity = 100%). Thus, we suggest the combination of Ki67I flow cytometric determination and immunophenotype as a reliable tool to classify canine lymphomas.

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.

Mismatch between transcriptomic and histopathologic picture of canine lymphomas

Lymphoma is one of the most common malignant tumours occurring in dogs. Since there is a constant need for new, more comprehensive laboratory diagnostic tools which permit the precise determination of many tumour-related factors we decided to verify whether the use of microarray analysis could be helpful in classifying lymphomas. The study was performed on samples collected from 7 dogs in which multicentric lymphoma was recognized. Among this group we were able to identify one sub-cluster of transcriptionally similar tumours, which completely differed in terms of the histopathological examination. Among them there were one diffuse large B cell lymphoma, one diffuse macronucleolated medium-sized cell lymphoma and one pleomorphic mixed small and large T-cell lymphoma. The lymphomas belonging to the sub-cluster differed from other analysed tumours in the expression of more than 100 genes of which only 18 were described earlier in regard to lymphomas.

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.

Evaluation of a B-cell leukemia-lymphoma 2-specific radiolabeled peptide nucleic acid-peptide conjugate for scintigraphic detection of neoplastic lymphocytes in dogs with B-cell lymphoma

OBJECTIVE

To evaluate use of a radiolabeled peptide nucleic acid-peptide conjugate (RaPP) targeting B-cell leukemia-lymphoma 2 (BCL2) mRNA for scintigraphic detection of neoplastic lymphocytes in dogs with B-cell lymphoma and to assess associations among RaPP uptake, time to tumor progression (TTP), and BCL2 mRNA expression.

ANIMALS

11 dogs with B-cell lymphoma and 1 clinically normal dog.

PROCEDURES

Scintigraphic images were acquired 1 hour after IV injection of the RaPP. Regions of interest (ROIs) were drawn around lymph nodes, liver, and spleen; ROI intensity (relative to that of an equally sized region of muscle in the same image) was measured. Each ROI was also subjectively categorized as positive or negative for increased RaPP uptake. Expression of BCL2 mRNA was determined via quantitative reverse transcriptase PCR assay of a lymph node sample from dogs with lymphoma. Associations among imaging results, TTP, and BCL2 mRNA expression were evaluated.

RESULTS

Increased RaPP uptake was detected in affected tissues of dogs with lymphoma. Dogs with superficial cervical lymph node ROIs categorized as negative (n = 8) for increased RaPP uptake had a significantly longer TTP than did dogs for which this ROI was considered positive (2). Measured intensity of mandibular and superficial cervical lymph node ROIs was negatively associated with TTP. Associations among BCL2 mRNA and ROI intensity or TTP were not significant.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased RaPP uptake at mandibular or superficial cervical lymph node ROIs may be a negative prognostic indicator in dogs with lymphoma. A larger investigation is needed to determine clinical value of the RaPP for disease detection and prognostication.

Diagnostic evaluation and treatment recommendations for dogs with substage-a high-grade multicentric lymphoma: results of a survey of veterinarians

The goal of this study was to survey veterinarians regarding their current initial diagnostic and treatment recommendations for dogs with substage-a high-grade multicentric lymphoma. A written survey was conducted at the 2009 Veterinary Cancer Society conference asking veterinarians to provide demographic information, initial staging diagnostics and treatment recommendations for canine lymphoma. The most commonly recommended staging diagnostics were complete blood count (100%), chemistry panel (100%), urinalysis (85%), lymph node cytology (88%), thoracic radiographs (84%), immunophenotyping (76%) and abdominal ultrasound (75%). The most commonly used first-line B-cell protocols combined the drugs L-asparaginase, cyclophosphamide, doxorubicin, vincristine and prednisone (L-CHOP, 51%). CHOP (30%) and other CHOP-based protocols (12%) were used as well. Thirty-one percent of responders treated B- and T-cell lymphomas differently. Protocol lengths varied from ≤ 16 weeks to >2 years. Current staging and treatment recommendations for canine lymphoma are varied. Efforts to standardize recommendations should be considered.

Uveodermatologic lymphoma in two young related Portuguese water dogs

PURPOSE

Canine lymphoma (CL) is one of the most common forms of spontaneous canine neoplasia. Improved understanding of the genetic and environmental factors associated with CL may provide benefits for the study of non-Hodgkin's and Hodgkin's lymphoma in humans. Uveodermatologic lymphoma is reported in a single household of Portuguese water dog, and the etiology is discussed.

METHODS

A 1-year-old female intact Portuguese water dog was referred to the Ophthalmology Service of the Veterinary Teaching Hospital of the Autonomous University of Barcelona because of acute blepharospasm of the right eye in association with a multinodular dermatosis. Physical and ophthalmological examination and a complete diagnostic work-up, including skin and ocular histopathology and immunohistochemistry, were performed. Three months prior, in Galicia (Spain), 1200 km away from Barcelona, a male dog of the same litter showed very similar oculodermatological clinical signs and skin histopathology, and immunohistochemistry were obtained.

RESULTS

The clinical diagnoses were anterior exudative uveitis, iridal masses, and secondary glaucoma. Histopathology and immunohistochemistry revealed a nonepitheliotropic lymphoma rich in B cell in dog 1 and rich in T cell in dog 2.

CONCLUSION

It is proposed that an underlying genetic predisposition could have played a role in the development of lymphoma in these two young related dogs.