Characterization of CD3+/CD20+ canine large-cell lymphoma

Immunophenotyping of canine large-cell lymphoma (LCL) for B-cell and T-cell surface antigens is commonly performed to better predict the clinical outcome. Expression of surface antigen CD3 is associated with T-cell malignancies; surface antigen CD20 is expressed on B cells. However, a small subset of canine LCLs expresses both CD3 and CD20 (CD3+/CD20+); this form of lymphoma remains poorly defined at the molecular level. In a retrospective study, we aimed to better characterize immunophenotypic properties and antigen receptor clonality of CD3+/CD20+ LCL. We selected formalin-fixed, paraffin-embedded tissues from 10 cases of CD3+/CD20+ LCL and breed-matched controls of peripheral large T-cell lymphoma (PTCL) and diffuse large B-cell lymphoma (DLBCL). Using PCR for antigen receptor rearrangement (PARR), we identified monoclonal T-cell receptor gamma (TCRγ) rearrangements in all CD3+/CD20+ cases. Three of 10 cases had monoclonal rearrangements in the immunoglobulin heavy chain (IgH), supportive of cross-lineage rearrangement. There was no significant difference in the frequency of antigen receptor rearrangement between CD3+/CD20+ and PTCL cases. In comparison with DLBCL, CD3+/CD20+ LCL had TCRγ rearrangement more frequently and IgH rearrangement less frequently, respectively. Immunolabeling of the B-cell marker PAX5 occurred less frequently in all CD3+/CD20+ LCL cases compared to the DLBCL controls. Immunolabeling for BCL-2 was robust, regardless of immunophenotype. Nuclear Ki67 positivity was variable in CD3+/CD20+ cases, indicating a heterogeneity in proliferation. Overall, cases of canine CD3+/CD20+ LCL had properties similar to PTCL, suggesting a similar histogenesis of these 2 subsets.

Significant increase in MIC-A and MIC-B and soluble MIC-A and MIC-B in canine lymphomas

Non-Hodkin's lymphoma (NHL) is the most frequent hematologic malignancy in humans and dogs. NKG2D is one of the most critical receptors on NK cells, recognizing their natural ligands on malignant cells such as A and B major histocompatibility complex-related proteins (MIC-A and MIC-B). Soluble molecules (sMIC-A and sMIC-B) can interfere with immune synapsis between NK cells and tumor cells, impeding NK cytotoxicity. The main objectives of this study were to analyze, in dogs with diffuse large B cell lymphoma, NK cell lymphoma, and reactive lymphadenopathies, the role of NK cells, their activating receptors NKG2D and NKp46, and their ligands MIC-A and MIC-B, as well as soluble molecules sMIC-A and sMIC-B. Thirty-six dogs with a possible diagnosis of NHL and eight healthy dogs were studied. NHL was diagnosed in 28 (78 %) dogs; in the other 8 (22 %), reactive lymphadenopathies were present. Most of the lymphomas corresponded to B cell NHL (82 %). The most predominant subtype was diffuse large B cell lymphoma (21, 71.5 %), followed by five cases (18 %) that were Non-B Non-T lymphomas (presumably NK cell lymphomas) and other B cell lymphomas (3, 10.5%). There were no cases of T cell NHL. MIC-A was positive in 7 of 27 (26 %) cases of NHL, and MIC-B in 20 of 27 (74 %) NHL. In non-malignant lymphadenopathies, three (37.5 %) dogs were positive for MIC-A, and five (62.5 %) expressed MIC-B. Dogs with lymphoma had higher numbers of NK cells than eight healthy dogs. In 15 dogs (12 cases with NHL and three cases with reactive adenopathies) and eight controls, there were no differences in the number of NK cells expressing NKP46 and NKG2D. NHL dogs had higher values of sMIC-A and sMIC-B. B-cell and NK cell lymphomas correspond to 86 % and 14 % of all canine lymphomas. MIC-A, MIC-B, and sMIC-A and sMIC-B were increased in canine lymphomas.

Colonic T-cell-rich, large B-cell lymphoma associated with equid herpesvirus 5 infection and secondary trans-colonic fistula in a horse

A 17-y-old Rocky Mountain gelding was presented to the Virginia-Maryland Veterinary Teaching Hospital because of a 4-wk history of anorexia, weight loss, lethargy, and fever of unknown origin. Abdominal ultrasound revealed lymphadenomegaly of the abdominal and colonic lymph nodes, thickening of the wall of the large colon, and a mass associated with the large colon. The horse was euthanized given a poor prognosis. On autopsy, an ~20-cm diameter mass was found within the mesocolon between the right ventral and right dorsal colon. The mass had invaded through the colonic walls and formed a fistula between the 2 involved lumina. On histologic evaluation, the mass consisted of small numbers of large neoplastic lymphocytes, numerous small lymphocytes, and many foamy macrophages. A diagnosis of T-cell-rich, large B-cell lymphoma was made based on immunohistochemical staining for CD79a, CD3, and Iba1; concurrent infection with equid herpesvirus 5 was confirmed with in-situ hybridization (ISH). To our knowledge, neither a trans-colonic fistula resulting from alimentary lymphoma in a horse nor detection of intralesional equid herpesvirus 5 in equine alimentary lymphoma by ISH has been reported previously.

T-cell-rich, large B-cell lymphoma in the brain of a horse

T-cell-rich, large B-cell lymphoma (TCRLBCL) is the most commonly diagnosed type of lymphoma in horses. Here we describe the clinical signs, neuropathology, immunohistochemistry (IHC), and PCR for antigen receptor rearrangement (PARR) analysis results of a TCRLBCL in the brain of an 8-y-old male Quarter Horse that was euthanized after acute anorexia, tremors, head pressing, falling, blindness, incoordination, and seizures. Autopsy revealed a firm, smooth, pale-yellow mass that expanded both lateral ventricles and the adjacent subcortical white matter. Histologically, the mass consisted of a densely cellular neoplasm composed of large, CD79+ neoplastic B-lymphocytes admixed with sheets of small, CD3+ reactive T-lymphocytes, Iba1+ histiocytes, MUM1+ plasma cells, and rare eosinophils supported by a fine fibrovascular stroma. Formalin-fixed, paraffin-embedded tissue scrolls were retrieved and subjected to PARR analysis, which revealed a clonal reaction in the immunoglobulin gene and a polyclonal reaction for the T-lymphocyte receptor gene, consistent with a neoplastic B-lymphocyte and reactive T-lymphocyte proliferation. The diagnosis of TCRLBCL was suspected histologically and confirmed based on IHC and PARR analysis.

DEVELOPMENT AND VALIDATION OF A NOVEL DUPLEX PROBE-HYBRIDIZATION QUANTITATIVE PCR FOR LYMPHOMA-ASSOCIATED MIROUNGINE GAMMAHERPESVIRUS 3 IN NORTHERN ELEPHANT SEALS (MIROUNGA ANGUSTIROSTRIS)

Recently, a novel gammaherpesvirus, miroungine gammaherpesvirus 3 (MirGHV3), was described in two juvenile elephant seals (Mirounga angustirostris) with diffuse large B-cell lymphoma. We developed and validated a quantitative (q)PCR for rapid detection of MirGHV3 and investigated its potential association with lymphoma. We developed a duplex probe-hybridization qPCR with MirGHV3 DNA polymerase (pol) as the target gene. Each primer-probe combination was cross-validated against the others. Interference was not seen when they were run in the same well as a duplex assay. Twenty-three samples from seven northern elephant seals were tested using the duplex assay. Viral DNA was detected by the assay in 9 of 9 (100%) tissues affected by lymphoma and in 6 of 14 (43%) samples from tissues unaffected by lymphoma. There was a strong correlation between viral copies detected with each of the assays (P=0.0002). Viral load was significantly higher in tissues affected by lymphoma than in those unaffected (P<0.0001). Excluding the virus-negative samples, viral load was still significantly higher in tissues affected by lymphoma than in those unaffected (P=0.0004). This is consistent with a potential role of MirGHV3 in oncogenesis in northern elephant seals, although more studies are needed to determine this definitively. The qPCR developed has utility for further investigations of MirGHV3.

Investigation of canine extracellular vesicles in diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCLs) are the most common lymphoproliferative diseases in dogs. DLBCL diagnosis to date has relied on histopathological analysis; however liquid biopsies have gained attention in recent years as a source of diagnostic and prognostic information. Liquid biopsies can be a source of circulating DNA, miRNA, circulating tumour cells or extracellular vesicles (EVs). In this study EVs were isolated from the plasma of healthy dogs, and dogs with lymphoma, and adenocarcinoma by iodixanol density gradient centrifugation. These EVs were positive for the EV markers CD63 and TSG101 and the pan-B cell markers CD79a, CD21, CD45, CD20. NTA analysis revealed that the DLBCL and adenocarcinoma dogs had elevated plasma EVs relative to the healthy dogs. Furthermore, the modal size of lymphoma EVs had decreased relative to healthy dogs while adenocarcinoma EVs were unchanged. This study demonstrates that the plasma EV population is altered in canine lymphoma patients in a manner similar to previous studies on human lymphomas. The similar changes to the EV population in dogs, together with the similar pathological features and treatment protocols in canine and human non-Hodgkin lymphomas would make dogs a good comparative model for studying the role of EVs in DLBCL development and progression.

Diffuse large B cell lymphoma and a novel gammaherpesvirus in northern elephant seals Mirounga angustirostris

Two emaciated male northern elephant seal (NES) Mirounga angustirostris pups were admitted to The Marine Mammal Center (Sausalito, California, USA) and treated for malnutrition. Complete blood counts showed a progressive moderate to marked leukocytosis characterized by a predominance of large monomorphic mononuclear cells of probable lymphoid origin, frequently with flower-shaped nuclei. Both seals were euthanized due to suspected lymphoid neoplasia. At necropsy, most lymph nodes in both pups were markedly enlarged, some with distinct white nodules, the spleens were diffusely enlarged, and the intestinal mucosae were thickened. Histopathologic features consistent with disseminated large cell lymphoma were identified to varying degrees of severity in lymph nodes, bone marrow, liver, tonsils, spleen, liver, intestines, kidneys, lower urinary tract, and several other organs. Immunohistochemical staining of neoplastic cells was most consistent with B lymphocyte origin, with most cells staining positively for Pax 5 and CD20 with admixed small CD3-positive T lymphocytes and CD204-positive macrophages. PCR and sequencing identified a novel gammaherpesvirus, herein called miroungine gammaherpesvirus 3, from affected tissues. This virus is in a clade outside of named genera that utilize hosts in the suborder Caniformia. The present study is the first description of diffuse large B cell lymphoma with leukemic manifestation and concomitant detection of a novel gammaherpesvirus in free-living NESs. Further research regarding the prevalence of this new gammaherpesvirus and its associated pathogenesis in this species is indicated.

Prognostic role of non-neoplastic lymphocytes in lymph node aspirates from dogs with diffuse large B-cell lymphoma treated with chemo-immunotherapy

Dogs with Diffuse Large B-Cell Lymphoma (DLBCL) benefit from the addition of active immunotherapy to traditional chemotherapy. We hypothesized that immune cells within neoplastic lymph nodes (LNs) may play a role in the tumor pathobiology and treatment response. The present study describes the composition and prognostic role of non-neoplastic lymphocytes in LNs of 59 dogs with treatment-naive DLBCL receiving chemo-immunotherapy. The percentage of small non-neoplastic cells and of CD5+, CD21+, CD4+ and CD8+ small cells was recorded via flow cytometry. CD4+/CD8+ and CD5+/large CD21+ cell ratios were calculated. The likelihood of progression significantly diminished with increasing percentage of small cells, CD5+ and CD8+ small cells, and CD5+/large CD21+ cell ratio, with decreasing CD4+/CD8+ ratio and in non-anemic dogs. Active immunotherapy is more effective in dogs with higher percentage of non-neoplastic lymphocytes at diagnosis. We lay the ground for future studies assessing the role of the immune system in the pathobiology of canine DLBCL.

Histiocytic Sarcoma in the Tarsus of a Cat

A 12-year-old Persian cat was examined for a firm swelling of the right tarsal region and enlargement of the corresponding right popliteal lymph node. Cytologic evaluation demonstrated a population of malignant cells consistent with large cell lymphoma. Necropsy revealed a multi-lobulated subcutaneous mass involving the tarsus with some extension into adjacent deep muscular tissue. Histologically, the mass was composed of round cells with eosinophilic cytoplasm and pleomorphic anisokaryotic nuclei. Evidence of articular and nodal infiltration by these cells was observed. Differential diagnoses included synovial sarcoma and histiocytic sarcoma. Neoplastic cells were negative for cytokeratin, CD79a, and CD3 and positive for CD18, vimentin, lysozyme, and alpha-1-antitrypsin, most consistent with a diagnosis of histiocytic sarcoma. This is the first report of a histiocytic sarcoma involving a joint of a cat. The final diagnosis was based on the light microscopic appearance in combination with the immunohistochemical stains.

Assessment of canonical NF-κB activity in canine diffuse large B-cell lymphoma

Companion dogs with spontaneous malignancies are clinically relevant models in which to study the corresponding human diseases and potential therapies. In both dogs and people, non-Hodgkin's lymphoma (NHL) is the most common hematopoietic malignancy. Diffuse large B-cell lymphoma (DLBCL) is the most common NHL subtype in dogs and people, sharing similar biologic, behavioral, genetic, and molecular characteristics in both species. One such molecular characteristic is the constitutive activation of the canonical NF-κB pathway, which in health regulates the expression of target genes that control cellular proliferation, survival, and immune and inflammatory responses as well as multidrug resistance. We found that canine and human DLBCL patients share similar NF-κB activity profiles. Using the cell-permeable NBD peptide, which blocks NF-κB signaling, we inhibited constitutive NF-κB activity and induced apoptosis of primary canine malignant B cells in vitro. In addition, we found that NBD peptide administration to dogs with relapsed B-cell lymphoma inhibited the expression of NF-κB target genes and reduced tumor burden. In this chapter, we describe our methods for processing canine malignant lymphoid tissue. We also describe our methods for treating the lymphocytes isolated from this tissue with NBD peptide and evaluating constitutive canonical NF-κB activity in these cells via immunoblot and electrophoretic mobility shift assay (EMSA). We highlight the nuances of working with canine primary cells.

A phase I clinical trial of systemically delivered NEMO binding domain peptide in dogs with spontaneous activated B-cell like diffuse large B-cell lymphoma

Activated B-Cell (ABC) Diffuse Large B-Cell Lymphoma (DLBCL) is a common, aggressive and poorly chemoresponsive subtype of DLBCL, characterized by constitutive canonical NF-κB signaling. Inhibition of NF-κB signaling leads to apoptosis of ABC-DLBCL cell lines, suggesting targeted disruption of this pathway may have therapeutic relevance. The selective IKK inhibitor, NEMO Binding Domain (NBD) peptide effectively blocks constitutive NF-κB activity and induces apoptosis in ABC-DLBCL cells in vitro. Here we used a comparative approach to determine the safety and efficacy of systemic NBD peptide to inhibit constitutive NF-κB signaling in privately owned dogs with spontaneous newly diagnosed or relapsed ABC-like DLBCL. Malignant lymph nodes biopsies were taken before and twenty-four hours after peptide administration to determine biological effects. Intravenous administration of <2 mg/kg NBD peptide was safe and inhibited constitutive canonical NF-κB activity in 6/10 dogs. Reductions in mitotic index and Cyclin D expression also occurred in a subset of dogs 24 hours post peptide and in 3 dogs marked, therapeutically beneficial histopathological changes were identified. Mild, grade 1 toxicities were noted in 3 dogs at the time of peptide administration and one dog developed transient subclinical hepatopathy. Long term toxicities were not identified. Pharmacokinetic data suggested rapid uptake of peptide into tissues. No significant hematological or biochemical toxicities were identified. Overall the results from this phase I study indicate that systemic administration of NBD peptide is safe and effectively blocks constitutive NF-κB signaling and reduces malignant B cell proliferation in a subset of dogs with ABC-like DLBCL. These results have potential translational relevance for human ABC-DLBCL.

Epigenetic silencing of TFPI-2 in canine diffuse large B-cell lymphoma

Epigenetic modifications are important early events during carcinogenesis. In particular, hypermethylation of CpG islands in the promoter region of tumor suppressor genes is a well-known mechanism of gene silencing that contributes to cancer development and progression. Tissue factor pathway inhibitor 2 (TFPI-2) is a tumor suppressor involved in invasiveness inhibition. Although TFPI-2 transcriptional silencing, through promoter hypermethylation, has been widely reported in several human malignancies, it has never been explored in lymphoma. In the present study TFPI-2 methylation and gene expression have been investigated in canine Diffuse Large B-cell lymphomas (cDLBCL). The methylation level of 23 CpGs located within the TFPI-2 promoter was investigated by bisulfite-specific PCR and next generation amplicon deep sequencing (GS Junior 454, Roche) in 22 cDLBCLs and 9 controls. For the same specimens, TFPI-2 gene expression was assessed by means of Real-time RT-PCR. Sequence analysis clearly demonstrated that TFPI2 is frequently hypermethylated in cDLBCL. Hypermethylation of the TFPI-2 promoter was found in 77% of DLBCLs (17 out of 22) and in one normal lymph node. Globally, dogs with DLBCL showed a mean methylation level significantly increased compared to controls (p<0.01) and analysis of hypermethylation by site identified 19 loci out of 23 (82%) with mean methylation levels from 2- to 120-fold higher in cDLBCL. Gene expression analysis confirmed a significant down-regulation of TFPI-2 (p<0.05) in DLBCLs compared with normal lymph nodes, suggesting that TFPI-2 hypermethylation negatively regulates its transcription. In addition, a significant positive correlation (p<0.01) was found between TFPI-2 methylation levels and age providing the first indication of age-associated epigenetic modifications in canine DLBCL. To conclude, our findings demonstrated that epigenetic dysregulation of TFPI-2, leading to its reduced expression, is frequently detected in canine DLBCL. In the next future, the aberrant TFPI-2 promoter hypermethylation may be considered in association with prognosis and therapy.

A pilot study evaluating changes in pancreatic lipase immunoreactivity concentrations in canines treated with L-asparaginase (ASNase), vincristine, or both for lymphoma

L-asparaginase (ASNase) is a common chemotherapy agent for the treatment of lymphoid malignancies. L-asparaginase has been reported to cause clinical pancreatitis in both humans and canines. Canine pancreatic lipase immunoreactivity (cPLI) is now a common diagnostic tool for evaluating pancreatitis in dogs. A total of 52 dogs were enrolled into this study. Canine pancreatic lipase immunoreactivity (cPLI) concentrations were evaluated before and after administration of ASNase, vincristine, or both. All dogs enrolled in the study were evaluated for signs compatible with clinical pancreatitis. No dogs receiving ASNase alone showed evidence of clinical pancreatitis after administration. Also, there was no statistically significant change in cPLI concentrations before or after treatment. Fourteen percent of dogs that received both vincristine and ASNase concurrently had elevated concentrations of cPLI after treatment. Of the 11 dogs with clinical signs compatible with pancreatitis after any chemotherapy treatment, no dog had a cPLI concentration > 400 microg/dL. In conclusion, ASNase did not cause clinical pancreatitis in this cohort of dogs but larger sample sizes are required to further validate this data.

Diagnostic value of ultrasonography in differentiating enteritis from intestinal neoplasia in dogs

One hundred and fifty dogs with histopathologically confirmed intestinal disease were evaluated retrospectively. Sixty-one dogs had enteritis and 89 dogs had intestinal neoplasia. Ultrasonographic findings including the thickness and distribution of the intestinal lesion, the integrity of intestinal wall layering, regional lymph node thickness, the location of the intestinal segment involved, and regional motility were evaluated. Dogs with intestinal tumor had wall thickness (1.5 cm) significantly greater than dogs with NSE lesions (0.6 cm; p < 0.001). Ninety-nine percent of dogs with intestinal tumor had loss of wall layering while 88% of dogs with NSE had normal or altered wall layering (p < 0.001). Dogs with NSE were significantly more likely to have diffuse lesion (72%) than dogs with intestinal tumor (2%; p < 0.001). Lymph node median thickness in 24/61 dogs with NSE was 1.00 cm. The median thickness of the lymph nodes in 56/89 dogs with intestinal tumors was 1.9 cm. A multivariate analysis showed that loss of wall layering alone was an excellent predictive factor in differentiating intestinal tumor from NSE. In our population, dogs with loss of intestinal wall layering were 50.9 times more likely to have a tumor than enteritis.

Histiocytic sarcoma in C57BL/6J female mice is associated with liver hematopoiesis: review of 41 cases

Forty-one cases of histiocytic sarcoma (HS) in C57BL/6J mice were histopathologically studied with special regard to unexpected associated hematopoietic disorders. These cases were retrieved among C57BL/6J female mice used as control mice in a chronic low-dose irradiation experiment. Hematopoietic characteristics were analysed by comparison to 41 disease-free mice from the same cohort. Tumoral involvement of the liver was observed in all 41 HS-bearing mice, followed by infiltration of the spleen (61.8%), lung (32.4%), bone marrow (14.3%), uterus (12.2%), lymph node (9.8%), and kidney (2.4%). By comparative analysis, we were able to demonstrate a significant association of HS with liver hematopoiesis (89.5% in HS group vs 15% in control mice, p < 0.00001), and with central hematopoietic disorders involving the myelocytic cells (decreased in HS, p = 0.003) and erythrocytic cells (increased in HS, p = 0.001). Microscopic characteristics of these 41 cases and physiopathology of the newly described hematopoietic features in HS are further discussed.

Clinicopathological and immunophenotypical features of canine intravascular lymphoma (malignant angioendotheliomatosis)

Intravascular lymphoma (IVL) is a rare angiotropic large-cell lymphoma in which neoplastic lymphocytes proliferate within the lumina of blood vessels in the absence of a primary extravascular mass or leukaemia. A retrospective review of veterinary medical records identified 17 cases of canine IVL. Spinal cord ataxia (seven dogs), posterior paralysis (one dog), seizures (four dogs) and vestibular disease (three dogs) dominated the clinical presentation. Haemorrhage, ischaemia, and occasional foci of vascular proliferation were found in tissue sections from affected dogs. Vessels, predominantly veins, throughout the body were frequently filled with neoplastic lymphocytes. Splenic involvement occurred in only one of 10 cases examined and bone marrow involvement was absent in four cases examined. Formalin-fixed paraffin wax-embedded tissues from 15 cases were examined immunohistochemically with streptavidin-biotin-horseradish peroxidase and a catalysed signal amplification system. The neoplastic cells were classified in eight cases as T cells (CD3+/IgG-/CD79a-), in one case as B cells (CD3-/CD79a.dim/IgG+), and in the remaining six cases as non-T, non-B (CD3-/IgG-/CD79a-). The clinical and pathological features of canine IVL closely resembled those of the human disease. In striking contrast to human cases, which are most often B-cell lymphomas, the immunophenotypes of the canine IVLs in this series were heterogeneous. The canine IVLs were derived primarily from T cells and non-T, non-B lymphocytes, B cells being found in only a single instance.

Small intestine large granular lymphoma in a horse

A 12-year-old Appaloosa gelding was referred to the Texas Veterinary Medical Center with a history of chronic diarrhea and weight loss. At necropsy, numerous oval, craterlike ulcers were observed throughout the small intestine. Histologically, these lesions were composed of a neoplastic proliferation of round cells with intracytoplasmic phosphotungstic acid-hematoxylin-positive granules. The tumor cells stained positively for the CD3 antigen and negatively for a B-cell marker. A diagnosis of large granular lymphoma was based on the morphologic and immunohistochemical characteristics of the neoplasm. The postmortem presentation of this case depicted unusual multifocal, ulcerative lymphomatous lesions throughout the small intestine without involvement of the regional lymph nodes. The histologic and ultrastructural morphology of the neoplastic lymphocytes was similar to that in previously reported cases of abdominal equine large granular lymphomas, but in this case the neoplasm was restricted to the small intestine.

Giant cell hepatitis in two young cats

A very rare case of the liver lesion characterized by formation of multinucleated giant hepatocytes with inflammatory cell infiltration were observed in two young (1.5 years and 2 years old) cats bearing thymic malignant lymphoma. Histopathological features of this liver lesion were very similar to giant cell hepatitis (GCH) in human neonates and infants. Therefore, the lesion was diagnosed as feline GCH.

Primary canine and feline nervous system tumors: intraoperative diagnosis using the smear technique

The recent application of neuroimaging techniques in veterinary neurology has led to the accurate localization of many types of intracranial lesions but has also created a clinical need, particularly with brain tumors, for a specific intraoperative diagnosis. For human brain tumors, a smear technique has been used successfully for many years to provide an extremely rapid, highly accurate intraoperative diagnosis. In similar smear preparations of intracranial lesions, obtained either by computed tomography (CT)-guided stereobiopsy or from a craniotomy, we have described distinguishing cytologic features of some primary spontaneous nervous system tumors in 80 dogs and 13 cats. A final diagnosis was confirmed by evaluation of paraffin-embedded sections from the same sample and, when appropriate, by immunocytochemical staining. Preliminary findings indicate that, in dogs and cats, this procedure is useful for rapid, accurate intraoperative diagnosis of many primary nervous system tumors. The distinguishing features of the canine and feline tumors bear a remarkably close resemblance to their human counterparts.

Malignant lymphoma in nasal cavity and paranasal sinuses of a dog

A case of a canine large cell type T-cell lymphoma, with features of high-grade malignancy is described. The tumour was found confined in the nasal cavity and the paranasal sinuses of a crossbred German Shepherd dog. Histological examination revealed the features of a highly malignant large cell lymphoma. Ultrastructurally, the lymphoid tumour cells bore cytoplasmic protrusions that interdigitated tightly. From a panel of tumour markers used, the neoplastic cells were stained only for vimentin. Immunophenotyping of the tumour cells by means of CD3, CD79, kappa-light chains and lambda-light chains detection was undertaken. The tumour stained only for CD3 and was classified as T-cell lymphoma.

Intravascular lymphoma presenting as bilateral panophthalmitis and retinal detachment in a dog

A seven-year-old, spayed female boxer was presented for sudden blindness and red eyes of one week's duration. Ophthalmic examination revealed bilateral uveitis with complete bullous retinal detachments. Initial diagnostic testing failed to reveal evidence of systemic disease. Cytopathology of subretinal aspirates confirmed the presence of macrophages with intracytoplasmic retinal pigment, epithelial and choroidal pigment, and monocytes. Tentative diagnoses were idiopathic uveitis and retinal detachment. The dog was treated with immunosuppressive doses of prednisone. The retinas reattached and vision returned. By two months, the dog became blind and systemically ill. Postmortem and histopathological examinations revealed intravascular lymphoma in multiple organs, including the eyes.

Large granular lymphocyte leukemia/lymphoma in six cats

This report describes six cases of feline large granular lymphocyte lymphoma identified by light microscopy on the basis of their characteristic azurophilic granulation in Giemsa-stained plastic sections and by electron microscopy on the basis of their typical granules. Although the granules of all the tumor cells were negative for peroxidase activity, they all demonstrated chloroacetate-esterase and acid phosphatase activity. All the tumors reacted with cross-reacting antibodies against the CD3 antigen (epsilon chain) and did not react with a cross-reacting monoclonal antibody directed against epitopes on cytoplasmic domains of the CD20 antigen. Three tumors had a positive reaction with a monoclonal human CD57-like antibody. This is highly suggestive of either a cytotoxic T cell or a natural killer cell origin of the neoplasias. In three cats, although other abdominal organs were affected to a variable extent, the main neoplastic lesions were localized in the gastrointestinal tract and the jejunal lymph nodes. In contrast, in the other three cats, organ involvement was more widespread, affecting the lung (two), myocardium (two), precardiac mediastinum (one), salivary gland (one), and spinal cord (one); in addition, leukemia was present in two of these cats. The data presented indicate that tumors made up of large granular lymphocytes occur more frequently in cats than previously assumed and that they share many characteristic features with specific subtypes of clonal disorders of large granular lymphocytes in humans.

Equine malignant lymphomas: morphologic and immunohistochemical classification

Gross lesions, microscopic appearance, and immunophenotyping are reported in a retrospective study of 31 cases of equine malignant lymphoma. Immunohistochemical studies were performed on archived formalin-fixed, paraffin-embedded tissues. Monoclonal antibodies to surface glycoprotein BLA.36 and intracytoplasmic domains of mb-1 and B29 were used to document the presence of B lymphocytes in the equine tumors. Polyclonal antibody to CD3 and monoclonal antibodies to T-lymphocyte markers CD3 and CD5 revealed the presence of variable numbers of T cells within the equine lymphomas. The neoplastic component of the equine lymphomas was determined through morphologic evaluation, immunophenotyping, and the use of proliferation markers Ki-67 and proliferating cell nuclear antigen. Equine malignant lymphomas were composed of a heterogeneous cell population. Most tumors contained B and T lymphocytes. Twenty-four horses had diffuse lymphomas derived from B lymphocytes. Thirteen of these lymphomas contained primarily neoplastic B lymphocytes. Eleven additional cases of diffuse large B-cell lymphoma contained from 40% to 80% nonneoplastic T lymphocytes and were classified as T-cell-rich, large B-cell lymphomas. This is the first description of T-cell-rich, B-cell lymphoma in the horse. Six tumors with a diffuse architecture were derived from T lymphocytes. Four T-cell tumors were large-cell tumors, 1 was a small-cell tumor, and in 1 tumor the size of the cells could not be determined accurately because of autolytic change in the tissues. One diffuse large-cell lymphoma did not react with either B- or T-cell markers.

Morphometric analysis of bovine lymphomas classified according to the National Cancer Institute Working Formulation

The National Cancer Institute Working Formulation (NCI-WF) for the subjective classification of human non-Hodgkin's lymphoma is readily applicable to the classification of bovine lymphomas. Forty-nine cases of bovine lymphoma were analysed morphometrically to see if nuclear size and cleavage were distributed continuously or discretely between different NCI-WF tumour cell types. The mean nuclear area (+/- standard error of the mean, SE) was significantly greater (P < 10(-6)) in cells from the different types of diffuse large-cell lymphoma than in cells from the different types of small-cell lymphoma (42.91 +/- 1.21 micron 2 vs 19.33 +/- 1.08 micron 2, respectively); there was no overlap between the two groups. The mean nuclear are (+/- SE) of cells from diffuse large-cell lymphomas was significantly greater (P < 10(-4)) than that of cells from small non-cleaved lymphomas (42.74 +/- 1.72 micron 2 vs 27.54 +/- 1.08 micron 2, respectively), and there was again no overlap between the two groups; these two cell types are difficult to distinguish by any criteria other than size. Additionally, the cell-to-cell variability in nuclear area within a given tumour was significantly greater (P < 0.001) for the diffuse large-cell type than for the small non-cleaved cell type. The mean nuclear form factor (+/- SE) and mean nuclear contour indices (+/- SE) of the diffuse large cleaved cell type (0.53 +/- 0.02 and 5.08 +/- 0.11, respectively) were significantly different (P < 0.01 to 10(-6)) from the same parameters in the diffuse large-cell type (0.82 +/- 0.01 and 3.94 +/- 0.04, respectively). Some of the major criteria of the NCI-WF used subjectively to discriminate between bovine lymphoma cell types were supported by morphometric measurements. The magnitude of the differences in nuclear morphological characteristics between bovine lymphoma cell types was such that there was no overlap.

The immunophenotypic characterization of bovine lymphomas

A prospective analysis of 38 cases of bovine lymphoma was performed. Thirty-five of the lymphomas were considered enzootic because of serologic or molecular biologic association with the bovine leukemia virus (BLV). The three remaining cases were in cattle < 1 year of age and were not associated with BLV and hence were considered sporadic lymphomas. Utilizing the national cancer Institute Working Formulation for the morphologic classification of human non-Hodgkin's lymphoma, 54.3% (19/35) of the enzootic lymphomas were classified as the diffuse large cleaved cell type. The cells of the 35 enzootic lymphomas expressed a consistent immunophenotype represented by MHCII+, gamma-heavy chain+, and lambda-light chain+; this constellation of markers indicated a mature B-cell phenotype. The three sporadic lymphomas failed to express MHCII antigen despite the presence of other B-cell antigens. There was no correlation between morphologic cell type and immunophenotype in these bovine lymphomas.

Morphological characteristics of a transplantable histiocytic sarcoma (HS-J) in F344 rats and appearance of renal tubular hyaline droplets in HS-J-bearing rats

A transplantable tumour (HS-J) was established from a spontaneous histiocytic sarcoma found in a 24-month-old male F344 rat. Serial transplantations (seven generations) were made in syngeneic male and female rats by means of intraperitoneal or subcutaneous implants, with a 100% take rate. Rats given HS-J implants developed large nodules locally, with metastasis to distant organs. HS-J tumours consisted mainly of round to oval cells with abundant cytoplasm, arranged in a compact sheet. Enzyme- and immuno-histochemical examination showed that neoplastic cells reacted with ED1 (rat monocyte/macrophage-specific antibody), lysozyme, alpha 1-antitrypsin and lysosomal enzymes (acid phosphatase and non-specific esterase), indicating derivation from cells of the monocyte/macrophage lineage. The majority of neoplastic cells were negative for ED2 (rat tissue macrophage-specific antibody). Abnormal accumulations of hyaline droplets in the proximal renal tubular epithelial cells were seen in HS-J-bearing rats. The droplets were faintly immunopositive for lysozyme, but negative for alpha-2u globulin and albumin. It was considered that excessive production of the protein by tumour cells might lead to subsequent overload in renal tubules. HS-J may prove beneficial for studying the biological behaviour of monocyte/macrophage-derived tumours in the rat.

Functional interleukin-2 receptors are expressed on natural killer-like leukemic cells from a dog with cutaneous lymphoma

We identified a dog with large granular lymphocytic leukemia and cutaneous lymphoma that exhibited constitutive expression of interleukin-2 (IL-2) receptors by the leukemic peripheral blood lymphocytes. The leukemic cells phenotypically resembled natural killer (NK) cells, and their surface IL-2 receptors were functional, as determined by the capacity to bind human recombinant IL-2 with high-affinity resulting in the transduction of proliferation signals and in the development of lymphokine-activated killer cell activity. These cells produced IL-2 spontaneously, and they may have maintained their proliferative state through an IL-2-dependent autocrine growth pathway. Our results indicate that neoplastic lymphocytes of syndromes that involve circulating leukemic cells with dermotropism can originate from NK-like cells. Additionally, the data also suggest that proliferative conditions such as these may be the result of the aberrant production of IL-2. Further, this case illustrates the potential for the use of hematopoietic malignancies in the dog as a suitable animal model for immune targeting of IL-2 receptors as a novel treatment approach for similar malignancies of human beings.

[Neoplasms originating from large granular lymphocytes in a dog and cats]

Clinical, cytological and pathological findings in three cases of large granular lymphoma in a dog and two cats are presented. These tumors consist of large granular lymphocytes, which have been in part classified as natural killer cells, based on their phenotype and functional aspects. It is likely that such tumors are more frequent than commonly appreciated, because they are only recognized as such in cytological preparations or in electron microscopy.

Primary splenic lymphoma in a horse

A well-demarcated solitary splenic mass (20 x 20 x 15 cm in size) containing hemorrhagic and necrotic foci was observed in a 4-year-old Thoroughbred stallion. Histologically, the mass consisted of lymphoma cells of the diffuse large non-cleaved type, with a high mitotic index and scattered macrophages that formed a starry sky pattern. The lymphoma cells revealed diffuse positivity for acid phosphatase and alpha naphthyl butyrate esterase, and were also positive for intracytoplasmic IgM on occasion, and mostly for proliferating cell nuclear antigen. Ultrastructural examination revealed moderately-developed rough endoplasmic reticulum sometimes with dilated cisternae. Thus, the diagnosis was a primary splenic lymphoma of B cell origin, but the exact reason for the absence of invasive growth or metastasis despite the high proliferative activity of this neoplasm was unclear.

Evaluating constraints that allow survival-adjusted incidence analyses in single-sacrifice studies

Ideally, analyses of tumor incidence data from long-term animal experiments should allow the incidence rates to vary with age, without restricting tumor lethality, without requiring data on cause of death, and without assuming independence of competing risks. This article focuses on nonparametric methods that not only satisfy these conditions, but also accommodate studies having just one sacrifice time, by constraining the effects of age on one of the three functions used to characterize the likelihood. Several constrained analyses were evaluated using data on over 18,000 mice from the ED01 study. Of the five constraints considered, only the assumption of constant differences between the death rates for animals with and without the tumor of interest produced reasonable results across a wide range of tumor lethalities.

Lymphoma involving large granular lymphocytes in cats: 11 cases (1982-1991)

Medical records of 11 cats with lymphoma involving large granular lymphocytes were reviewed. All 9 cats tested were FeLV-negative. Ten cats had a history of anorexia, lethargy, vomiting, or diarrhea, and had lymphoma involving abdominal viscera. The most common site of tumor in these cats was the jejunum. One cat had cutaneous masses caused by dermal and epidermal infiltration with neoplastic large granular lymphocytes. The most common hematologic abnormality was leukocytosis, characterized by neutrophilia with a left shift (7 cats); 2 cats had a left shift without neutrophilia. None of the cats had lymphocytosis, but immature large granular lymphocytes were found in the blood of 4 cats. The most common serum biochemical abnormalities were hypoalbuminemia (10 cats), hypocalcemia (10 cats), hypoproteinemia (9 cats), high aspartate transaminase activity (9 cats), and hyperbilirubinemia (8 cats). Large granular lymphocytes were characterized by abundant cytoplasm containing distinct azurophilic granules that varied in size and number. The most common cytochemical staining pattern included detection of alpha-naphthyl butyrate esterase, acid phosphatase, and beta-glucuronidase activities. On examination of histologic sections, granules stained weakly eosinophilic with Giemsa and moderately with periodic acid-Schiff reaction. Ultrastructurally, the granules appeared membrane bound and contained an electron-dense matrix in 4 cats.

Classification of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphomas

A retrospective histologic study was made of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphoma. This classification scheme was found to be readily applicable to bovine lymphoma. Most of the cell types described in the National Cancer Institute Working Formulation occurred in this series of bovine lymphomas, but the distribution of cell types varied markedly compared to that of human beings. Eighty-nine percent (1,067/1,198) of bovine lymphomas were high-grade tumors. The diffuse large cell type and its cleaved variant comprised 65.9% of all bovine lymphomas. Similar to the dog, but in marked contrast to human beings where at least 34% of non-Hodgkin's lymphomas were follicular, follicular tumors were found to be extremely rare in cattle (0.3% or 4/1,198). The prevalence of cell types varied significantly between the enzootic and sporadic lymphomas. The cleaved variant of the diffuse large cell type constituted 38% (406/1,072) of enzootic lymphomas versus 14% (18/126) of sporadic lymphomas. The mitotic index (100 x oil immersion field, 175 microns in diameter) of enzootic lymphomas (3.72 +/- 0.06, mean +/- standard error) was significantly greater than the mitotic index of sporadic lymphomas (2.82 +/- 0.17). We concluded that the cleaved variant of the diffuse large cell type with high mitotic index is characteristic of enzootic lymphoma. This characteristic high-grade cell type may be a consequence of the viral etiology of the enzootic form of bovine lymphoma.

Transplantation of canine malignant lymphomas in the nude and SCID mouse

Canine lymphoid tumours, which share a number of features with human non-Hodgkin's lymphomas, were grafted in nude or SCID mice. Two (DL.24,DL.31) out of eight lymphomas and two (DL.31,DL.35) out of three lymphomas produced a sub-cutaneous (s.c.) tumour in nude and SCID mice respectively. In all animals, the s.c. tumours that developed at the inoculation site were regularly associated with metastasis to the regional lymph nodes, and also to the spleen, liver and bone marrow in SCID mice. The four transplanted tumours, with a pseudo-diploid canine karyotype, were diffuse large cell lymphomas as the initial dog tumours, and could be immunophenotypically characterized by surface immunoglobulins, MHC-class 2 and Thy-1 antigens. Serially transplanted lymphomas in nude and SCID mice may hence be used for further studies of these tumours.

Immunological and ultrastructural characterization of true histiocytic lymphoma in the northern pike, Esox lucius L

An epidemic of a malignant neoplasm occurs in northern pike, Esox lucius L., from the Aland Islands of Finland. The neoplasm is morphologically similar to other pike hemic tumors reported in other areas of the world. Pike normal tissues showed evolutionary conservation with the mammalian intermediate filament proteins cytokeratin, desmin, vimentin, neurofilament protein, and glial fibrillary acidic protein; tumor cells are positive for vimentin, suggesting that the neoplasm is of mesenchymal origin. Hemic tissue mononuclear cells undergo polyclonal stimulation by the known mammalian T- and B-lymphocyte mitogens phytohemagglutinin P, concanavalin A, tuberculin-purified protein derivative, and lipopolysaccharide W; pike tumor cells are nonreactive. Pike normal hemic tissue mononuclear cells are variously positive for surface and cytoplasmic immunoglobulins, using rabbit anti-pike immunoglobulin M and cross-reactive mouse anti-carp immunoglobulin M antibodies; tumor cells, however, are not positive. The tumor cells were also diffusely stained with sodium fluoride-sensitive nonspecific esterase. The foregoing suggest that the neoplasm is not of B-lymphocytic or plasmacytic derivation, while the T-lymphocytic as opposed to monocytic derivation cannot be excluded on the basis of marker studies. The ultrastructural studies, however, suggest a neoplasm of histiomonocytic derivation, while the absence of sinusoidal infiltration of tumor cells to head kidney, spleen, liver, or peripheral blood suggests that it is a piscine analogue of human true histiocytic lymphoma. Population dynamics studies indicate that the neoplasm affects primarily sexually mature males 5 to 6 yr of age, but does not at present appear to be a major factor affecting Aland pike populations.

Utilization of cytoplasmic lysozyme immunoreactivity as a histiocytic marker in canine histiocytic disorders

Immunoreactive lysozyme was readily detectable in canine histiocytic disorders including systemic histiocytosis, malignant histiocytosis and granulomatous panniculitis. Lysozyme was less reliable as a histiocytic marker in cutaneous histiocytoma; forty percent of these tumors were negative for lysozyme expression. The marked heterogeneity in lysozyme expression in cutaneous histiocytoma may indicate that a proportion of these tumors show relatively primitive histiocytic differentiation and do not express lysozyme. Alternatively, this same proportion may exhibit a phenotype akin to cutaneous Langerhans cells which do not contain lysozyme. Lysozyme was not detectable in the tumor cells in lymphomatoid granulomatosis, atypical cutaneous histiocytoma, and histiocytic lymphosarcoma. Other evidence that these three disorders do not represent true histiocytic proliferative disorders is discussed.

Use of radiotherapy for the treatment of intranasal tumors in cats: six cases (1980-1985)

Six cats with intranasal neoplasia treated with radiotherapy were evaluated. The mean survival time from the initiation of radiotherapy was 19 months, with 2 cats still known to be alive. Two cats died for reasons unrelated to the primary tumor. One cat had no clinical evidence of nasal tumor 41 months after treatment, but was lost to further follow-up evaluation.

The incidence of naturally-occurring primary brain tumours in the laboratory rat

Histological analysis of 90 spontaneous primary tumours of the brain observed among 8960 ageing rats (Sprague-Dawley-derived) revealed 55 granular-cell meningiomas, 19 neoplastic reticuloses, 11 neuroglial tumours, 4 pineal tumours, and one pleomorphic, meningeal sarcoma. Although all these tumour types can occur in man and other animal species, the high incidence of granular-cell tumours, and the low degree of differentiation of some neuroglial and pineal tumours, appear to be characteristic attributes of the rat.

Malignant lymphoma in a colony of Macaca arctoides

Malignant lymphoma occurred in six Macaca arctoides from a colony of 83 animals during a 30-month period. The cells of two neoplasms had T cell markers. Concurrent disease processes included atypical mycobacterial disease in four macaques and progressive multifocal leukoencephalopathy in one.

Malignant lymphoma and Hodgkin's disease in baboons (Papio sp.)

Four cases of spontaneous malignant lymphoma and one of Hodgkin's lymphoma in baboons at the Southwest Foundation for Biomedical Research were studied and described. These cases were in animals of both sexes that varied in age from 6 to 25 years, and were in residence at the Foundation from 2 to 24 years, during which time there was no known exposure to carcinogenetic agents. Attempts to isolate an etiological viral agent or demonstrate viral particles in lymphoid tissue were unsuccessful.

Aging changes in lymphopoietic and myelopoietic organs of the annual cyprinodont fish, Nothobranchius guentheri

The thymus of aging annual, cyprinodont fish, Nothobranchius guentheri and Cynolebias adloffi begins to undergo senescent changes at approximately four months. At this time, the histopathology reveals increased amounts of connective tissue, epithelial cysts and myoid cells, but decreased numbers of thymocytes. At 12 months, of the 50 fish observed at 10 stages from day 15 and 1, 2, 4, 6, 8, 9, 10, 11, 12 months the maximum time of senescence, there was an increased incidence of tumors in the oral cavity, connective tissue, kidney and liver in all 5 fish. At least in the kidney, the malignant transformation was classified as nodular-type histiocytic lymphoma. It is of interest that development of these tumors occurs during peak senescent changes in the thymus, supporting the view that as fish age, accompanied by atrophy of the thymus, the immune system is less vigorous and there is an increase in the incidence of cancer.

Microgliomatosis in a Schnauzer dog

Microgliomatosis was found in the central nervous system of a 7-year-old male Standard Schnauzer. History, neurologic examination, laboratory tests and electrodiagnostics could not localize the disease process in the central nervous system. The animal was not treated, continued to deteriorate, and was euthanatized approximately 8 weeks after clinical signs were first detected. Diagnosis was made upon histologic examination of the brain.

Malignant lymphoma in macaques: a clinicopathologic study of 45 cases

Malignant lymphoma was diagnosed in 42 rhesus macaques (Macaca mulatta) and 3 stumptail macaques (M. arctoides) between February 1969 and December 1977. The distribution of tumor masses in the tissues of individual animals varied widely. Solitary tumor masses were present in 14 animals and multiple masses in the remaining 31 animals. Visceral lymph nodes, gastrointestinal tract, heart, and kidneys were most commonly affected. Peripheral lymph nodes were rarely involved. Most malignant lymphomas were of an undifferentiated cell type, although tumors of histiocytic, lymphocytic, poorly differentiated, and mixed lymphocytic and histiocytic cell types were also observed. Concurrent bacterial and/or viral infections were evident in 30 of the 45 macaques with malignant lymphoma. Amyloidosis was present in 9 animals. This high incidence of malignant lymphoma suggested that their immune responses were abnormal. The development of malignant lymphoma in the macaques may have been secondary to or enhanced by immunodeficiency.