Canine T-cell lymphomas: a morphological,immunological, and clinical study of 46 new cases

The aim of this study is to report 46 new cases of canine T-cell lymphomas among a series of 140 lymphomas studied by immunophenotyping (incidence 32.8%). According to the updated Kiel classification adapted to the canine species, 13 were classified as low-grade and 33 as high-grade lymphomas. Among the low-grade lymphomas, five were small clear-cell lymphomas, three were pleomorphic small-cell lymphomas, and five mycosis fungoides. Among the high-grade cases, there were 11 pleomorphic mixed-, small-, and large-cell lymphomas, 6 pleomorphic large-cell lymphomas, 11 lymphoblastic lymphomas, and 5 unclassifiable high-grade plasmacytoid lymphomas. The cytohistologic features were highly suggestive of a T-cell phenotype on the basis of cell morphology (irregular nuclei and clear cytoplasms) (30/46 cases), a T-cell zone pattern, and the presence of hyperplastic postcapillary venules (22/46 cases). All 46 cases were CD3+ CD79a-, and among 34 cases investigated for CD4 and CD8 expression, 13 were CD4+CD8-, 13 were CD8+CD4-, and 8 were CD4CD8 double positive or double negative. The pleomorphic mixed lymphomas were mainly CD4+CD8- (6/7) and the lymphoblastic lymphomas were double positive or double negative (6/8). The main clinical, hematologic, and biochemical features were generalized (28/46) or regional lymphadenopathy (16/46), hepatosplenomegaly (15/46), extranodal involvement (11/46), mediastinal mass (9/46), and leukemia (8/46), which were mainly present in cases of lymphoblastic lymphomas and hypercalcemia (16/46).     

Inactivation of the p16 cyclin-dependent kinase inhibitor in high-grade canine non-Hodgkin's T-cell lymphoma

The significance of p16/Rb tumor suppressor pathway inactivation in T-cell non-Hodgkin's lymphoma (NHL) remains incompletely understood. We used naturally occurring canine NHL to test the hypothesis that p16 inactivation has specific pathologic correlates. Forty-eight samples (22 T-cell NHL and 26 B-cell NHL) were included. As applicable, metaphase- or array-based comparative genomic hybridization, Southern blotting, promoter methylation, and Rb phosphorylation were used to determine the presence, expression, and activity of p16. Fisher's exact test was used to test for significance. Deletion of p16 (or loss of dog chromosome 11) was restricted to high-grade T-cell NHL (lymphoblastic T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified). These were characterized by a concomitant increase of tumor cells with Rb phosphorylation at canonical CDK4 sites. Rb phosphorylation also was seen in high-grade B-cell NHL (diffuse large B-cell lymphoma and Burkitt-type lymphoma), but in those cases, it appeared to be associated with c-Myc overexpression. The data show that p16 deletion or inactivation occurs almost exclusively in high-grade T-cell NHL; however, alternative pathways can generate functional phenotypes of Rb deficiency in low-grade T-cell NHL and in high-grade B-cell NHL. Both morphologic classification according to World Health Organization criteria and assessment of Rb phosphorylation are prognostically valuable parameters for canine NHL.     

Clinical, laboratory, and histopathologic features of equine lymphoma

Clinical, laboratory and tissue findings from 37 horses with lymphoma were investigated. Horses ranged in age from 0.3 to 20.5 years (median 5.0 years) and included 18 females and 19 males. Weight loss (n = 25) and ventral edema (n = 21) were the most common historical and physical abnormalities. The most common laboratory abnormalities were hyperfibrinogenemia (n = 26), hypoalbuminemia (n = 19), anemia (n = 19), leukemia (n = 14), hyperglobulinemia (n = 13), and thrombocytopenia (n = 13). Thirty-four tumors involved multiple lymphoid tissues and abdominal or thoracic organs, and 3 tumors were restricted to cutaneous and subcutaneous sites. Histopathologically, all tumors diffusely effaced normal lymph node architecture. Tumor cell morphology was heterogeneous in 17 tumors, and 8 tumors had marked histiocytic and multinucleated giant cell infiltrates. Extensive necrosis or focal fibrosis was present in 22 and 4 lymphomas, respectively. Staining of tumor sections with antibodies against CD3 and CD79alpha molecules resulted in classification of T-cell (n = 26) or B-cell (n = 7) origin. Four tumors could not be classified. Most T-cell tumors comprised small to medium CD3(+) lymphocytes, whereas 5 of 7 B-cell tumors were infiltrated by numerous small T lymphocytes and classified as T-cell-rich B-cell lymphoma. Neither estrogen nor progesterone receptor expression was consistently identified by immunochemical assessment of tumor tissues. Fresh tumor cells from 6 horses bound antibodies reactive with equine CD4, CD5, CD8, CD21, or major histocompatibility class II molecules, confirming T-cell (n = 5) or B-cell origin (n = 1). These findings suggest that T-cell lymphoma is more common than B-cell lymphoma in horses and that inflammation, possibly from tumor cytokine production, is frequent.     

Genomic organization of the T-cell receptor gamma gene and PCR detection of its clonal rearrangement in canine T-cell lymphoma/leukemia

Because the T-cell receptor gamma (TCRgamma) gene is rearranged at an early stage of T-cell development in both TCRalphabeta and TCRgammadelta lineages, it has been preferentially targeted to detect T-cell clonality in human lymphoma/leukemia. We isolated 22 independent cDNA clones encoding canine TCRgamma and the following analysis of nucleotide sequences using the dog genome database revealed that the canine TCRgamma locus contains at least four repertories of variable genes that can be organized into two distinct subgroups and six repertories of joining genes belonging to two distinct subgroups according to the nucleotide sequence similarity. The findings allowed us to design PCR primers that were directed to the conserved or specific nucleotide sequences for each subgroup of variable and joining genes. By using four different combinations of primers, a PCR-based analysis was performed on cell samples collected from T-cell lymphoma/leukemia and B-cell lymphoma cases and hyperplastic and normal lymph nodes. All cell samples from 11 T-cell malignancy cases exhibited clonal amplification by two out of four primer combinations. This finding was considered to be valuable in PCR-based analysis for detecting T-cell clonality in canine lymphoma/leukemia.     

Aberrant phenotypes and quantitative antigen expression in different subtypes of canine lymphoma by flow cytometry

Flow cytometry may be a useful tool to analyze lymphoma samples that are obtained from fine needle aspirations (FNA). This study aimed to determine if flow cytometric analysis add more objective and standardized information on the cellularity and morphology of lymphoma cells to conventional cytology. The typical immunophenotype of different lymphoma subtypes was assessed and leukocyte marker expression was evaluated to determine which antigens were more frequently over- or under-expressed in these lymphoma subtypes. Fifty FNA lymph node samples were evaluated from canine lymphomas. Thirty-one samples were identified to be of B-cell origin, sixteen were identified to be of T/NK-cell origin and three cases were classified as acute lymphoblastic leukaemia with lymph nodes involvement. The most common B-cell lymphoma subtypes were centroblastic lymphomas, whereas three cases were atypical and classified as B-large cell pleomorphic lymphomas. Among the T/NK lymphomas, small clear cells, large and small pleomorphic mixed cells, large granular lymphocytic cells and small pleomorphic cells were identified. Aberrant phenotypes and/or antigen under/over regulation was identified in thirty out of forty-seven lymphoma cases (64%; 18/31 B-cell=58% and 12/16 T-cell=75%). In B-cell lymphomas the most frequent finding was the diminished expression of CD79a (45%). CD34 expression was also observed in four cases (13%). Among T-cell lymphomas the prevalent unusual phenotype was the under-expression or absence of CD45 (25%). These findings reveal flow cytometry may be useful in confirming the diagnosis of lymphoma, as the technique allows one to add useful information about morphology of the neoplastic cells and identify antigenic markers and aberrant phenotypes.     

Feline gastrointestinal lymphoma: mucosal architecture, immunophenotype, and molecular clonality

Gastrointestinal lymphomas were identified in 120 cats between 1995 and 2006. Lymphomas were classified according to the World Health Organization (WHO) scheme. Cats with mucosal T-cell lymphoma (n = 84) predominated and had a median survival of 29 months. Mucosal T-cell lymphoma matched WHO enteropathy-associated T-cell lymphoma (EATCL) type II. Epitheliotropic T-cell infiltrates were present in 62% of cats and occurred as clusters or diffuse infiltrates of small to intermediate-sized T cells in villous and/or crypt epithelium. Similar lymphocytes infiltrated the lamina propria in distinctive patterns. Cats with transmural T-cell lymphoma (n = 19) had a median survival of 1.5 months. Transmural T-cell lymphoma matched WHO EATCL type I. Epitheliotropic T-cell infiltrates were present in 58% of cats. Large lymphocytes (n = 11), mostly with cytoplasmic granules (LGL-granzyme B+) (n = 9) predominated. Transmural extension across the muscularis propria characterized the lesion. Both mucosal and transmural T-cell lymphomas were largely confined to the small intestine, and molecular clonality analysis revealed clonal or oligoclonal rearrangements of T-cell receptor-γ in 90% of cats. Cats with B-cell lymphoma (n = 19) had a median survival of 3.5 months. B-cell lymphomas occurred as transmural lesions in stomach, jejunum, and ileo-cecal-colic junction. The majority were diffuse, large B-cell lymphomas of centroblastic type. In conclusion, T-cell lymphomas characterized by distinctive mucosal architecture, CD3 expression, and clonal expansion predominated in the feline gastrointestinal tract.     

Diagnosis of mediastinal masses in dogs by flow cytometry

BACKGROUND: Biopsy of mediastinal masses can be invasive, but the procedure may be necessary if cytology of a mass aspirate is inconclusive. The 2 most common mediastinal masses, lymphoma and thymoma, may both be comprised of small lymphocytes. We investigated the ability of flow cytometry to distinguish between these 2 neoplasms. HYPOTHESIS: Flow cytometry of mediastinal mass aspirates may provide a definitive diagnosis of thymoma or lymphoma, reducing the need for biopsy. ANIMALS: Dogs with mediastinal masses presenting to the Veterinary Teaching Hospital/Animal Cancer Center were included in the study. METHODS: Aspirates obtained over 2 years that met the inclusion criteria (i.e. sufficient viable cells and a definitive diagnosis by means other than flow cytometry) were analyzed by flow cytometry to determine the percentage of cells expressing B- and T-cell markers, and co-expressing CD4 and CD8. RESULTS: All cases of thymoma (n = 6) consisted of > or = 10% lymphocytes coexpressing CD4 and CD8, a phenotype that is characteristic of thymocytes, whereas 6 of 7 lymphomas contained <2% CD4+CD8+ lymphocytes. The CD4+CD8+ lymphoma could be readily distinguished flow cytometrically from thymoma by light scatter properties. The phenotypes of the remaining lymphomas were CD4+ T cell (4), CD34+ (1) and B cell (1). CONCLUSIONS: Our studies demonstrate that flow cytometry is a useful tool for discriminating mediastinal masses. Lymphocyte-rich mediastinal masses could be unambiguously identified by flow cytometry in 13/13 cases.     

T-cell-derived malignant lymphoma in the boxer breed

The boxer breed of dog is at high risk for a variety of neoplasms including lymphoma. In this observational study, tissue sections from boxer dogs with lymphoma were immunostained for T and B lymphocyte distinction, and the results compared with similar studies carried out on lymphoma tissues from temporally selected cohorts of golden retriever and rottweiler dogs. The frequency of T‐cell lymphomas was significantly (P < 0.001 for all comparisons) higher in the boxers than in the rottweilers or golden retrievers. We are unaware of other reports linking immunotype of canine lymphoma with breed; whether other brachycephalic breeds of dogs have a similar preponderance of T‐cell lymphoma awaits further study.     

Nasal and nasopharyngeal lymphoma in cats: 50 cases (1989-2005)

Lymphoma is the most common nasal cavity tumor in cats, yet few reports specifically address the anatomic, immunohistologic, and cytologic features of this neoplasm. Fifty cats were diagnosed with lymphoma at necropsy, via biopsy or by cytology alone. Ten cats displayed multiorgan involvement, and in 2 of these the involvement was limited to the cerebellum and frontal cortex, respectively. Of the tumors, 41 of 50 (82%) were classified as nasal lymphoma, 5 of 50 (10%) were classified as nasopharyngeal lymphoma, and 4 of 50 (8%) involved both nasal and nasopharyngeal tissue. Histologically, all were considered diffuse lymphoid neoplasms and no cats displayed features of follicular lymphoma. Of the 44 cases available for slide review by the pathologist, 40 of 44 (91%) were classified as immunoblastic lymphoma, 2 of 44 (5%) as diffuse large cell, and 1 as diffuse mixed; 1 was unclassified. Of the 45 cats for which immunohistochemical stains were available, 32 were uniformly positive for CD79a, 7 were uniformly CD3 positive, and 6 had a mixed population of CD79a and CD3 cells. Epithelioptropism was exhibited in 4 of 5 (80%) cats in which there was sufficient epithelium present for evaluation. Of those 4, 3 were B-cell and 1 was a granulated T-cell lymphoma. In the 21 cats which nasal cytology was performed, 15 were cytologically diagnosed with lymphoma; the diagnoses in the remaining five cats were inflammatory (n = 4), normal lymphoid tissue (n = 1), or nondiagnostic (n = 1). The most common biochemical abnormalities were panhyperproteinemia in 26/46 (57%) of cats and hypocholesterolemia in 11/46 (24%) of cats.     

Cytomorphological and immunohistochemical features of lymphoma in ferrets

Twenty ferrets with histopathologically diagnosed lymphoma were classified cytomorphologically and immunohistochemically. According to site of origin, multicentric, gastrointestinal, mediastinal and cutaneous lymphomas accounted for 8 (40%), 9 (45%), 2 (10%) and 1 case (5%), respectively. According to the National Cancer Institute Working Formulation (NCI-WF), low-, high- and intermediate-grade lymphomas accounted for 4 (20%), 4 (20%) and 12 cases (60%), respectively. The 4 low-grade lymphomas showed no mitotic figures, whereas all 4 high-grade lymphomas exhibited > or = 3 mitotic figures (median,6). Higher grade thus appears to be associated with a higher number of mitotic figures. Immunohistochemical examination of 18 specimens, excluding 2 insufficient specimens, showed that 16 (88.9%) and 2 (11.1%) lymphomas were of T-cell origin and B-cell origin, respectively. According to the combination of the NCI-WF and immunophenotypes, all 4 low-grade lymphomas (2 multicentric, 1 gastrointestinal, and 1 cutaneous lymphoma) were classified as diffuse small lymphocytic lymphoma of T-cell origin. Of the 12 intermediate-grade lymphomas (6 multicentric, 4 gastrointestinal, and 2 mediastinal lymphomas), 11 were classified as diffuse mixed-cell lymphoma, and 1 as diffuse large cell lymphoma. Of these 11 lymphomas, 2 (both multicentric) were of B-cell origin, 7 (3 multicentric, 3 gastrointestinal, 1 mediastinal) were of T-cell origin, and 2 (1 multicentric, 1 mediastinal) were of unknown cell origin. The remaining 1 lymphoma (gastrointestinal) was of T-cell origin. All 4 high-grade lymphomas (gastrointestinal) were classified as diffuse immunoblastic lymphoma of T-cell origin.     

Laboratory findings, histopathology, and immunophenotype of lymphoma in domestic ferrets

Lymphoma is a common tumor in ferrets, but anatomic distribution, histomorphology, immunophenotype, laboratory abnormalities, and response to chemotherapy are incompletely defined. In this study, lymphoma was diagnosed by histopathology of tumor tissue in 29 ferrets ranging in age from 0.8 to 8.5 years, including 12 males and 17 females. Tumors involved the viscera of the abdominal cavity (n = 11), thoracic cavity (n = 1), or abdominal and thoracic cavities (n = 7); the skin (n = 2); or the viscera of both body cavities plus other sites (n = 8). Microscopically, all tumors had diffuse architecture. Assessment by histomorphology and immunophenotype classified tumors as peripheral T-cell lymphoma (n = 17), anaplastic large T-cell lymphoma (n = 5), anaplastic large B-cell lymphoma (n = 4), diffuse large B-cell lymphoma (n = 1), and Hodgkin-like lymphoma (n = 2). Cytologic evaluation of tumor tissue was diagnostic in 11 of 13 cases. Twenty-two of 27 ferrets had anemia, 2 had leukemia, and 5 were neutropenic. Common comorbid disorders were adrenal disease (n = 27) and insulinoma (n = 6). Tumors most frequently involved mesenteric lymph nodes, while enlargement of peripheral lymph nodes was uncommon (n = 3). Ferrets with Hodgkin-like lymphoma had massive enlargement of single lymph nodes. Mean survival of ferrets not immediately euthanized was 5.0 months (T-cell lymphoma) and 8.4 months (B-cell lymphoma). Ferrets treated with chemotherapy survived an average of 4.3 months (T-cell lymphoma, n = 9) or 8.8 months (B-cell lymphoma, n = 4). Results indicate that lymphomas in ferrets most commonly affect abdominal viscera, may be amenable to cytologic diagnosis, are frequently associated with anemia and, in some cases, may be chemosensitive, resulting in relatively long survival times.     

Genetic and epidemiological investigation of a birth cohort of boxers

The aim of this project, which ran from 1 January 1994 to 1 January 1999 (and which will be continued up to 2004), was to study mortality, disease incidence, and risk factors in a birth cohort of purebred boxer dogs born between January 1994 and February 1995 in the Netherlands (n = 2629). The ancestry of the boxer dogs in the cohort was considered a major risk factor. Special attention was given to genetic disorders, because a system for genetic counselling was being planned; however, non-genetic risk factors were also studied. Participation by breeders and owners of boxer dogs was very high. Pup mortality was 22% and was mainly caused by individual pup factors. Between 2 months and 4 years of age, 123 (7.5%) dogs died; the survival rate was 92.5%. The main causes of death were epilepsy (n = 23), heart disease (n = 22), and traffic injury (n = 13). Over the same age range, on average a boxer dog suffered about 4.25 times from a non-serious disease, mainly of the gastro-intestinal tract, upper respiratory tract, or locomotion system, but 20% had a serious, chronic disease. A relatively high heritability estimate (h2) was found for four diseases: cheilo-palatoschisis (h2 = 0.27), cryptorchism (h2 = 0.24), lesions of cruciate ligaments and menisci (h2 = 0.28), epilepsy (h2 = 0.36). Selection by means of genetic counselling, according to a programme developed on the basis of the results of this study, can reduce the frequency of these genetic diseases in purebred populations of boxer dogs. This genetic counselling programme will also be effective in other breeds of dog because it is based on linking specific pedigree and health information with a generally applicable method of estimating breeding values.     

Lineage differentiation of canine lymphoma/leukemias and aberrant expression of CD molecules

Multiparameter flow cytometry analysis and specific cluster differentiation (CD) molecules were used to determine the expression profiles of B- and T-cell antigens on lymph node preparations from 59 dogs with generalized or multisystemic lymphoma. Lymph node samples from 11 healthy dogs were labeled to validate the specificity of antibodies and to formulate guidelines for interpretation of the results obtained from lymphoma samples. In normal lymph nodes, T-lymphocytes expressing CD3, CD4, or CD8 beta represented 59+/-11%, 43+/-8%, or 16+/-5% of the total cells, whereas B-lymphocytes expressing either CD21 or surface IgM (IgM) represented 37+/-9% or 14+/-5%, respectively. Small lymphocytes could be distinguished from large lymphocytes by forward light scatter. Of the patient samples 29 different breeds were represented with Golden and Labrador retriever being the most common. The lymphoma samples segregated into three groups based on CD antigen expression. Thirty cases predominantly expressed one or more combinations of CD79a, IgM, and CD21 representing a B-cell lineage. Three B-cell cases also expressed the stem cell antigen, CD34. Sixteen cases expressed one or more combinations of CD3, CD4, and CD8 consistent with a T-cell lineage and CD3+CD4+CD8--phenotype was the most common. Thirteen cases showed a mixed expression profile for T- and B-cell antigens and in three cases CD14 was highly expressed. Clinical response was poorest for T-cell lymphomas. Leukemic states occurred in all three phenotypes; but mixed cell cases had the greatest proportion. Dual immunofluorescence staining confirmed co-expression of T-cell (CD3) and B-cell antigens (CD79a or CD21) on neoplastic lymphocytes of six mixed cell cases. In one mixed cell case, dual immunostaining identified lymphocyte populations that stained mutually exclusive for CD79a and CD3. Six mixed cell lymphomas tested by PCR showed clonality for rearranged antigen receptor. Four cases that were CD79a+CD3+ had TCRgamma chain gene rearrangements, whereas two cases that were CD3+CD8+CD21+ had Ig heavy chain rearrangement. One case expressing multiple CD molecules (CD3+CD8+CD21+CD14+) was PCR negative for both Ig and TCRgamma gene rearrangement and could not be classified into a B- or T-cell lineage. We show for the first time co-expression of B- and T-cell markers on lymphoma cells that had specific T- or B-cell gene rearrangements. These findings suggest that aberrant CD molecule expression is not an uncommon finding in canine lymphomas and is a useful diagnostic marker for malignancy.     

Distribution of T cells in the Endometrium of the Mare 6 and 48 h after Insemination

Contents
In order to study the T-cell response after the introduction of semen into the uterine cavity, the distribution of helper T cells (CD4+) and cytotoxic/suppressor T cells (CD8+) was examined immunohistochemically in endometrial biopsy specimens. Endometrial tissue samples were obtained from 19 gynaecologically healthy mares during oestrus, both before and 6 or 48 h after deposition of a single dose of neat stallion semen. An increase (p = 0.04) in the numbers of helper T cells (CD4+) was observed at 6 h after insemination; thereafter the number of CD4+ cells decreased to pre-insemination values by 48 h after insemination. No significant variations in numbers of CD8+ cells were recorded either 6 or 48 h after insemination. There seems to be an early (6 h), recruitment of helper T cells into the equine endometrium after semen deposition, which might be related to the activation of the endometritis-like reaction seen as part of the equine uterine immune defence system during oestrus.     

Bovine leukemia virus high tax molecular clone experimentally induces leukemia/lymphoma in sheep

Sheep were inoculated with high tax coded pBLV-IF (H group, Nos.1-5) of bovine leukemia virus (BLV), wild tax coded pBLV-IF (W group, Nos. 6-11), or control plasmid (C group, Nos. 12-14). During the observation period (4 to 46 months), 5 of 5 cases in H group and 3 of 6 cases (Nos. 6, 7, 9) in W group became positive for gp 51. Only 1 case in H group became leukemic, and one case each of H and W groups developed lymphoma. In No. 3, lesions were found in multiple organs including the lymph nodes, gastrointestinal tract following abomasum, and heart. In No. 6, lesions of lymphoma were found only in the jejunum and heart. Morphologically, small to middle-sized lymphocytic neoplastic (NP) cells were found in both cases, but lymphoblastic NP cells were found only in No. 3. By immunohistochemical examination, the phenotypes of NP cells were determined as CD1-, CD4-, CD5- -, CD8alpha-, sIgM+, lambda light chain+, B-B4+, MHC class II+ in both case. The results of this study indicate that inoculation of pBLV-IF can induce lymphocytic and lymphoblastic leukemia/lymphoma in sheep. Additionally, it is suggested that the expression rate of tax gene is not associated with the development of leukemia/lymphoma in sheep experimentally inoculated with pBLV-IF.     

Effects of active egg white product/ Clostridium butyricum Miyairi 588 additive on peripheral leukocyte populations in periparturient dairy cows

The leukocyte populations of periparturient dairy cows were analyzed after administration of active egg white/Clostridium butyricum Miyairi additive. Sixty-eight Holstein milking cows were divided into 3 groups. Group A was administered active egg white product (AEWP)/Clostridium butyricum Miyairi 588 (Miyairi 588) additive (n=23). Group B was administered Miyairi 588 only (n=23), and Group C was the control group (n=22). The challenged groups were administered 100 g of AEWP + Miyairi 588, or Miyairi 588 alone, daily for 60 days from 1 month before until 1 month after paturition. Blood samples were collected from all groups three times (1 month before, 1 week after and 1 month after parturition) for analysis of the peripheral leukocyte population. The results showed significantly higher numbers of CD4+ cells in Group A compared with Group C 1 week after paturition. AEWP/Miyairi 588 additive may enhance the number of CD4+ T cells in periparturient dairy cows.     

Cutaneous T-cell lymphoma in a heifer with increased serum lactate dehydrogenase activity

A 1-year-old heifer from an enzootic bovine leukemia virus (BLV)-free breeding herd was examined for numerous cutaneous plaques on the neck, shoulder, back, perineum, and tail. Impression smears of the skin lesions contained a large population of neoplastic lymphoblastic cells. Hematologic findings included mild anemia, neutrophilia, and lymphocytosis. The serum activity of lactate dehydrogenase (LDH) was moderately increased at admission (4712 U/L), and remained increased despite normal to minimally increased activities of liver- and muscle-specific enzymes. The heifer was serologically negative for BLV. Because of declining condition and poor prognosis, the heifer was euthanized on day 37 after presentation. At necropsy and on histologic examination, epitheliotropic and folliculotropic cutaneous lymphoma, with generalized involvement of lymph nodes and spleen and infiltration of liver and kidney, was diagnosed. Immunophenotyping results (CD79-, CD3+) were consistent with a lymphoma of T-cell origin. We concluded that cutaneous T-cell lymphoma had spread to the other internal organs, and that the neoplasm likely contributed to increased serum LDH activity.     

High-grade canine T-cell lymphoma/leukemia with plasmacytoid morphology: a clinical pathological study of nine cases.

The aim of this study is to determine the clinical, morphological, and immunophenotypical presentation of 9 cases of a particular type of canine T-cell lymphoma/leukemia. The morphological presentation was a diffuse infiltration of small, medium-sized, or large blast cells with eccentric nuclei, hyperbasophilic cytoplasm, and a juxtanuclear, pale cytoplasmic area, giving a plasmacytoid appearance and suggesting a B-cell morphology. Surprisingly, all 9 cases were of T-cell phenotype (CD3+). Among the 7 immunophenotyped cases, 4 were CD4-/CD8+, 2 CD8+/CD4+, and 1 CD4+/CD8-. The median Ki-67 index was 65.7%, which placed this lymphoma in the high-grade group. This type of lymphoma/leukemia was found in dogs between 1 and 11 years of age, with a median age of 5.8. The male-female ratio was 0.8 for a reference population of 1.04. The most significant clinical findings were lymphadenopathy either generalized or localized in all cases, a mediastinal mass in 4 cases, bone marrow involvement in 7 cases, hypercalcemia in 4 cases, along with an aggressive clinical course and a poor response to chemotherapy in all cases, with a median disease-free survival time of 3 months.     

Prognostic significance of morphological subtypes in canine malignant lymphomas during chemotherapy

The aim of this study was to determine the response of different morphological subtypes of canine lymphoma to a standardized therapeutic protocol. Diagnosis of lymphoma was based on cytohistological analysis and immunophenotyping with antibodies against CD3 and CD79a of an enlarged lymph node or an extranodal mass. Fifty-seven cases were classified according to the updated Kiel classification adapted to the canine species, into 24 B-cell lymphomas (20 centroblastic polymorphic and four Burkitt-type subtypes), and 33 T-cell lymphomas (10 pleomorphic mixed, 10 lymphoblastic, eight unclassifiable high grade plasmacytoid, and five small clear-cell subtypes). All dogs were clinically staged at diagnosis. The protocol used l-asparaginase, vincristine, cyclophosphamide, doxorubicin, and prednisone. First remission duration and overall survival time were evaluated. Although the T-cell phenotype was associated, on the whole, with a poor prognosis, as previously reported in veterinary and human medicine, the study showed significant prognostic differences between the B- and the T-cell subtypes of canine lymphoma and suggests that clinico-morphological characterization of the disease is justified in dogs, as in humans.     

Histopathologic features, immunophenotyping, clonality, and eubacterial fluorescence in situ hybridization in cats with lymphocytic cholangitis/cholangiohepatitis

Feline lymphocytic cholangitis is a poorly characterized disease complex with respect to histologic lesions, immunophenotype, and etiopathogenesis. Seventy-eight cases of feline lymphocytic cholangitis (n = 51) and feline hepatic lymphoma (n = 27) were reviewed using standardized histopathology, immunophenotyping (B cell and T cell), polymerase chain reaction for T-cell receptor (TCR) gene rearrangement, and fluorescence in situ hybridization (FISH) for eubacteria. Five histopathologic features in cases of lymphocytic cholangitis assisted in its differentiation from hepatic lymphoma: bile duct targeting (n = 32, 62.7%), ductopenia (n = 9, 17.6%), peribiliary fibrosis (n = 37, 72.5%), portal B-cell aggregates (n = 36, 70.6%), and portal lipogranulomas (n = 38, 74.5%). The majority of lymphocytic cholangitis cases (n = 35, 68.6%) were T cell predominant; 15 (29.4%) had an equal mix of B cells and T cells, and 1 (1.9%) had a B cell-predominant infiltrate; 66.6% of hepatic lymphoma cases were T-cell lymphomas. TCR clonality results were unexpected, with 17.1% of cases of lymphocytic cholangitis having clonal or oligoclonal populations and with T-cell lymphomas having variable TCR clonality (63.6% clonal or oligoclonal, 36.3% polyclonal). The majority of lymphocytic cholangitis (n = 32 of 36, 88.8%) and all hepatic lymphoma cases had no detectable eubacteria using FISH. As demonstrated here, bile duct targeting, ductopenia, peribiliary fibrosis, portal B-cell aggregates, and portal lipogranulomas are lymphocytic cholangitis features that, along with polyclonal TCR (83%), help differentiate it from hepatic lymphoma. No strong evidence was found implicating in situ bacterial colonization as an etiopathogenesis of lymphocytic cholangitis.