A case of T-cell chronic lymphocytic leukemia progressing to Richter syndrome with central nervous system involvement in a dog

An 8-year-old neutered Beagle dog was presented with polyuria and polydipsia. Routine clinicopathologic testing showed a significant lymphocytosis and proteinuria. Lymphocytes were of small to intermediate in size with a mature morphology. Infectious disease screening was negative. PCR for antigen receptor gene rearrangements showed a clonal T-cell receptor (TCR) rearrangement consistent with T-cell chronic lymphocytic leukemia (CLL). Bone marrow cytology showed <30% lymphocytes, while the proportion in splenic fine-needle aspirate cytology was considered increased. The dog was initially monitored but started on prednisolone and chlorambucil therapy 2 months later due to worsening clinical signs and progressive lymphocytosis. After an additional 2 weeks, the dog developed multifocal spinal pain and single-node lymphadenomegaly. Cytology of the lymph node showed a monomorphic population of large lymphoblasts consistent with lymphoma. Cytology of a cerebrospinal fluid sample also showed large lymphoblasts. PCR for antigen receptor gene rearrangement at both sites showed a clonal TCR rearrangement of the same molecular size as in the initial leukemic cells. The dog was diagnosed with a transformation of the CLL to Richter syndrome (RS) with involvement of the central nervous system (CNS). Therapy was started with L-asparaginase and an increased dose of prednisolone; however, the dog was euthanized due to progressive clinical signs. To our knowledge, this is the first report of canine RS with direct involvement of the CNS.     

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.     

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.     

Treatment of chronic lymphocytic leukaemia in three dogs with melphalan and prednisolone

Three adult dogs with chronic lymphocytic leukaemia (CLL) were successfully treated with melphalan and prednisolone. Based on the immunophenotypic analysis of leukaemic cells, two dogs were diagnosed with B cell CLL and one dog was tentatively diagnosed as having T cell CLL. One dog with B cell CLL had IgM monoclonal gammopathy. The clinical signs and haematological abnormalities associated with CLL in the three dogs improved with the administration of cytoreductive melphalan (3 to 5 mg/m2/day) and prednisolone (4.3 to 30 mg/m2/day) for eight to 210 days. There were no severe adverse effects except a mild increase in plasma alkaline phosphatase activity. Melphalan and prednisolone therapy may achieve remission with few side effects in dogs with CLL.     

A case of chronic lymphocytic leukemia masked by Cushing’s disease in a dog

A 12-year-old, 3.5-kg, intact female dog was presented with polyuria, polydipsia, and a pendulous abdomen. Laboratory examinations showed elevated hepatobiliary enzyme levels and neutrophilic leukocytosis. The adrenocorticotropic hormone stimulation test confirmed hyperadrenocorticism (HAC). Trilostane therapy managed the clinical condition and cortisol concentration. However, lymphocytosis and nonregenerative anemia developed after HAC remission. Bone marrow aspiration analysis revealed a lymphoproliferative disorder with a clonal T-cell population. Accordingly, the patient was diagnosed with T-cell chronic lymphocytic leukemia (CLL) and concurrent HAC. Thereafter, chemotherapy was initiated, which improved the lymphocytosis. However, euthanasia was performed because of worsening quality of life at 45 weeks after the first presentation. These results suggested that CLL could be masked by excessive endogenous cortisol and discovered after HAC remission.     

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.     

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.     

Hepatosplenic lymphoma in a dog

We describe a case of a dog with hepatosplenic lymphoma, a disease characterized by infiltration of the liver, spleen, and bone marrow with gammadelta T cells, absence of peripheral lymphadenopathy, and an aggressive clinical course. Physical examination findings, hematologic and biochemical abnormalities, and clinical course of the disease in this patient were similar to those in humans. Immunophenotyping of liver and spleen aspirates supported an antemortem diagnosis of T-cell lymphoma consistent with hepatosplenic lymphoma. The diagnosis was confirmed postmortem by a combination of routine histopathology, showing a consistent pattern of organ involvement, and immunohistochemistry showing the infiltrating neoplastic lymphocytes to be T cells expressing the gammadelta T-cell receptor. To our knowledge, this is the first reported case of hepatosplenic lymphoma in a dog.     

Morphologic, immunohistochemical, and molecular characterization of hepatosplenic T-cell lymphoma in a dog

A 13-year-old neutered male Jack Russell Terrier (Parson Russell Terrier) was presented to the Texas Veterinary Medical Center with a history of lethargy, depression, vomiting, and fever. The dog had mildly regenerative anemia, severe thrombocytopenia and low antithrombin activity. Marked splenomegaly was found on physical examination and imaging studies, and malignant round cell neoplasia and marked extramedullary hematopoiesis were diagnosed on aspirates of the spleen. The dog underwent exploratory laporatomy and splenectomy. Because of a rapid decline in clinical condition postsurgery, the dog was euthanized. Splenic and hepatic biopsies were submitted for histopathologic evaluation. A neoplastic population of round cells was found throughout the splenic parenchyma and within hepatic sinusoids. The neoplastic cells stained strongly positive for CD3 (T-cell marker) and were negative for CD79a (B-cell marker) and lysozyme (histiocytic marker). A diagnosis of T-cell lymphoma was confirmed by assessment of T-cell clonality using canine-specific polymerase chain reaction-based techniques. Although expression of the gammadelta T-cell receptor was not evaluated, this case shares many similarities with a rare syndrome in humans known as hepatosplenic gammadelta T-cell lymphoma.     

Chronic lymphocytic leukemia transformation into high‐grade lymphoma: a description of Richter's syndrome in eight dogs

Richter's syndrome (RS) is the development of an aggressive lymphoma in patients with chronic lymphocytic leukaemia (CLL). In humans, RS occurs in 2–20% of CLL, which transform into diffuse large B‐cell lymphoma but reports in dogs are scarce. This study retrospectively describes eight dogs with CLL progressing into RS. A database including 153 dogs with CLL (93T CD8+ and 55 B‐CLL) was interrogated and RS was demonstrated in eight cases (representing 5.2% of total CLL): two with T‐cell (2.2% of T CLL) and six with a B‐cell immunophenotype (10.9% of B‐CLL). When RS occurred, lymphocytes were decreased compared to CLL. Five dogs had anaemia and two dogs thrombocytopenia. Frequent clinical signs included lymph node swelling, coughing, vomiting, neurological signs and weight loss. Independently from the therapy, RS was associated with a short survival (median 41 days). RS should be considered as an unfavourable evolution in canine CLL.     

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.     

Unicentric extranodal lymphoma of the upper eyelid conjunctiva in a dog

A case of conjunctival lymphoma in a 4-year-old Siberian husky is reported. A large red mass protruding from the conjunctiva of the upper eyelid of the right eye was present. Irritation, blepharospasm and epiphora were revealed on initial ophthalmic examination. After anti-inflammatory treatment, surgery was performed. Histologically, the mass consisted of large polygonal cells with a high nucleus to cytoplasm ratio, moderate amounts of slightly eosinophilic cytoplasm, pleomorphic nuclei with vesicular chromatin and prominent multiple nucleoli. Mitotic figures were frequent. Approximately 70% of the neoplastic cells were CD3 positive and CD79alpha negative. On the basis of histologic and immunohistochemical findings, a diagnosis of intermediate-grade, diffuse large-cell lymphoma with T-cell immunophenotype was made. The surgical area healed uneventfully and, although chemotherapy was not received, after 12 months the dog exhibited no recurrence. To the authors' knowledge, this is the first report of unicentric extranodal conjunctival lymphoma in a dog.     

Chronic lymphocytic leukemia in dogs and cats: the veterinary perspective.

Chronic lymphocytic leukemia (CLL) in dogs and cats shares many similarities with its human counterpart but also has significant differences. In marked contrast to people, CLL in dogs and cats is primarily a T-lymphocyte proliferation. Cytotoxic T-cell proliferations with granular lymphocyte morphology predominate in dogs, and T helper cell proliferations seem to be most common in cats with CLL. Immunophenotyping and assessment of clonality by molecular genetic analysis are newer adjunctive tools in veterinary medicine that are useful in the characterization and diagnosis of CLL in dogs and cats. The clinical presentation, typical hematologic findings, diagnosis, course of disease, prognosis, and therapy of CLL in dogs and cats are discussed.     

Immunophenotype predicts survival time in dogs with chronic lymphocytic leukemia

Background: Chronic lymphocytic leukemia (CLL) is a hematologic disorder in dogs, but studies on prognostic factors and clinical outcome are lacking. In people, several prognostic factors have been identified and currently are used to manage patients and determine therapy. Objectives: The aim of the study was to determine if the immunophenotype of neoplastic cells predicts survival in canine CLL. Design: Retrospective study. Animals: Forty‐three dogs with CLL. Procedures: Records of dogs with a final diagnosis of CLL were reviewed. For each included dog, a CBC, blood smear for microscopic reevaluation, and immunophenotyping data had to be available. Data on signalment, history, clinical findings, therapy, follow‐up, as well as date and cause of death were retrieved. Results: Seventeen dogs had B‐CLL (CD21+), 19 had T‐CLL (CD3+ CD8+), and 7 had atypical CLL (3 CD3? CD8+, 2 CD3+ CD4? CD8?, 1 CD3+ CD4+ CD8+, and 1 CD3+ CD21+). Among the variables considered, only immunophenotype was associated with survival. Dogs with T‐CLL had approximately 3‐fold and 19‐fold higher probability of surviving than dogs with B‐CLL and atypical CLL, respectively. Old dogs with B‐CLL survived significantly longer than did young dogs, and anemic dogs with T‐CLL survived a significantly shorter time than dogs without anemia. Conclusions: Although preliminary, results suggested that immunophenotype is useful to predict survival in dogs with CLL. Young age and anemia are associated with shorter survival in dogs with B‐CLL and T‐CLL, respectively.     

Immunophenotypic comparison of blood and lymph node from dogs with lymphoma

Peripheral blood and lymph node tissue from 12 dogs with lymphoma was immunophenotyped. Additionally, the bone marrow was immunophenotyped in 6 dogs. The lymphomas were characterized as B-cell in 11 dogs and T-cell in 1 dog. Immunophenotypic patterns in the peripheral blood and bone marrow were variable. The trend in dogs with B-cell lymphoma was normal to increased percentage of IgG-positive cells, decreased percentage of pan-T-positive cells, decreased percentage of CD4-positive cells, and decreased CD4/CD8 ratio. Simultaneous immunophenotyping of lymph node, blood and bone marrow cannot be recommended routinely without further studies to document its value as an independent prognostic indicator. However, it is potentially useful for tumor staging and monitoring remission, especially in lymphoma patients with a leukemic phase.     

Large granular lymphocyte lymphoma in the skin and urinary bladder of a dog

A 10-year-old female Cavalier King Charles Spaniel presented with hematuria, pollakiuria and skin rash. Based on the histopathological and cytological examination of the skin and bladder mucosa, the dog was diagnosed with large granular lymphocytic (LGL) lymphoma of the bladder and skin. The dog responded well to the initial chemotherapy with nimustine for 3 months. Since recurrence of skin erosion and bladder wall thickening were observed, the dog was subsequently administered chemotherapy with other anticancer drugs, including chlorambucil, vincristine, doxorubicin, L-asparaginase, cytosine arabinoside, and cyclophosphamide. The dog survived for 11 months and died due to tumor-related disseminated intravascular coagulation. This is the first report of a canine case of LGL lymphoma in the skin and bladder.     

Vertebral polyostotic lymphoma in a young dog.

An unusual clinical presentation of lymphoma with vertebral involvement in a dog is reported. A 20-month-old intact female Golden Retriever presented with progressive paraparesis and anorexia. Complete blood count and serum biochemistry profile demonstrated pancytopenia and hypercalcemia. Ventral fusion of the lumbar vertebrae by new bony tissue deposition was evident on X-ray and CT scan. Fine needle aspiration revealed neoplastic lymphoid cells in lymph nodes and bone marrow. Histologically, vertebral bone and osteophytes, liver, bone marrow, kidney, and lymph nodes were diffusely infiltrated by neoplastic, lymphoid cells, with scant cytoplasm and round hyperchromatic nuclei. Polyostotic and medullary T-cell lymphoma with spondylosis was diagnosed. Lymphoma mainly affecting bone is uncommon in the dog. The present case differs from previously described polyostotic lymphomas in clinical signs of the disease, mainly attributable to spondylarthrosis. In addition, lymphomatous proliferation was associated with osteoproductive lesions of the vertebrae.     

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

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

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.     

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.