Presumed pseudo-Pelger-Huët anomaly and basophilia secondary to chronic lymphocytic leukemia in a dog.

A 10-year-old neutered male Maltese dog was presented for an investigation of lymphocytosis. The dog was up-to-date on vaccinations and deworming. Physical examination did not reveal any significant abnormalities. A complete blood cell count (CBC) showed mild leukocytosis with moderate lymphocytosis, basophilia, and moderate neutropenia, but no significant left shift or toxic change. Serum biochemistry and urinalysis were unremarkable. All performed tests for infectious agents common in this geographical region were negative. No significant abnormalities were found on abdominal ultrasound examination. Multiparametric flow cytometry of peripheral blood showed a CD8+ T-cell lymphocytosis, and PCR for antigen receptor rearrangement revealed a clonal expansion of the T-cell receptor gamma chain genes. A clinical diagnosis of chronic lymphocytic leukemia (CLL) was made, and follow-up was recommended. On Day 48 post-presentation, the CBC showed mild non-regenerative anemia (NRA), moderate leucocytosis due to moderate to marked lymphocytosis, basophilia, and a marked increase in hyposegmented neutrophils with mild toxic change in the absence of neutrophilia or neutropenia. Treatment with chlorambucil and prednisolone was initiated. On Days 87 and 197 post-presentation, the CBC showed mild NRA, with progressively decreasing numbers of hyposegmented neutrophils. The dog remained without clinical signs. Basophilia and probable pseudo-Pelger-Huët anomaly were possibly secondary to CLL. To the authors' knowledge, this is the first report of these two hematologic conditions secondary to CLL in dogs. Recognition of a pseudo-Pelger-Huët anomaly is clinically relevant to avoid misinterpretation as a marked left shift due to severe inflammation and prevent unnecessary urgent therapeutic actions.

Assessment of Y chromosome copy number alterations in non-neoplastic and neoplastic leukocytes of male dogs.

The loss of the Y chromosome (ChrY), also known as LOY, is a common genetic alteration observed in men. It occurs in non-neoplastic cells as an age-related change as well as in neoplastic cells of various cancer types. While well-documented in humans, LOY has not been extensively studied in non-human mammals. In this study, we developed simple digital PCR-based assays to assess the copy number of ChrY relative to the X chromosome (ChrX) and chromosome 8 (Chr8) to evaluate ChrY numerical alterations in male canine DNA specimens. Using these assays, we analyzed non-neoplastic leukocytes from 162 male dogs without hematopoietic neoplasia to investigate the occurrence of age-related LOY in non-neoplastic leukocytes. Additionally, we examined 101 tumor DNA specimens obtained from male dogs diagnosed with various types of lymphoma and leukemia to determine whether copy number alterations of the ChrY occur in canine hematopoietic cancers. Analysis of the 162 non-neoplastic leukocyte DNA specimens from male dogs of varying ages revealed a consistent ∼1:1 ChrY:ChrX ratio. This suggests that age-related LOY in non-neoplastic leukocytes is rare or absent in dogs. Conversely, a decreased or increased ChrY:ChrX ratio was detected in canine neoplastic leukocytes at varying frequencies across different canine hematopoietic malignancies (P = 0.01, Fisher's exact test). Notably, a higher incidence of LOY was observed in more aggressive cancer types. To determine if this relative LOY to ChrX was caused by changes in ChrY or ChrX, we further analyzed their relative copy numbers using Chr8 as a reference. Loss of ChrX relative to Chr8 was found in 21% (9/41) of B-cell lymphomas and 6% (1/18) of non-T-zone/high-grade T-cell lymphomas. In contrast, a subset (29%, 4/14) of T-cell chronic lymphocytic leukemia showed gain of ChrX relative to Chr8. Notably, no relative LOY to Chr8 was detected indolent hematopoietic cancers such as T-zone lymphoma (0/9) and chronic lymphocytic leukemia of B-cell (0/11) and T-cell origins (0/14). However, relative LOY to Chr8 was present in more aggressive canine hematopoietic cancers, with incidences of 24% (10/41) in B-cell lymphoma, 44% (8/18) in non-T-zone/high-grade T-cell lymphoma, and 75% (6/8) in acute leukemia. This study highlights both similarities and differences in LOY between human and canine non-neoplastic and neoplastic leukocytes. It underscores the need for further research into the role of ChrY in canine health and disease, as well as the significance of LOY across various species.

B-cell leukemia in an adult sheep.

B-cell leukemia is a rare form of hematologic neoplasia in sheep, especially in adult animals. We present a case report of a 5-year-old WhiteFace Sheep wether with suspected acute lymphoblastic leukemia. The patient, a second-generation relative of ewes experimentally inoculated with atypical scrapie, exhibited acute lethargy and loss of appetite. Laboratory investigation revealed marked leukocytosis, lymphocytosis, and abnormal serum chemistry panel results. Microscopic examination of blood and bone marrow smears exhibited a high percentage of large neoplastic cells with lymphoid characteristics. Histopathologic analysis of the spleen, liver, lungs, and other organs confirmed the presence of widespread tissue infiltration by neoplastic cells. Immunohistochemical labeling demonstrated strong intracytoplasmic labeling for CD20, consistent with B-cell neoplasia. Flow cytometric analysis confirmed the B-cell lineage of the neoplastic cells. Screening for bovine leukemia virus, which can experimentally cause leukemia in sheep, yielded a negative result. In this case, the diagnosis of B-cell leukemia was supported by a comprehensive panel of diagnostic evaluations, including cytology, histopathology, immunohistochemistry, and immunophenotyping. This case report highlights the significance of accurate diagnosis and classification of hematologic neoplasia in sheep, emphasizing the need for immunophenotyping to aid in the diagnosis of B-cell leukemia. It also emphasizes the importance of considering spontaneous leukemia as a differential diagnosis in sheep with lymphoid neoplasia, especially in the absence of circulating infectious diseases.

B-cell small lymphocytic lymphoma in a free-ranging South American fur seal (Arctocephalus australis).

Lymphomas are malignant neoplasms of the hematopoietic system arising from lymphocytes with highly variable biologic behavior. B-cell small lymphocytic lymphoma (B-SLL) is a non-Hodgkin lymphoma infrequently described in domestic and wild animals. The present study describes a case of B-SLL in a free-ranging adult male Arctocephalus australis in Brazil. The main necropsy findings included poor body condition, generalized lymphadenomegaly, severe and diffuse splenomegaly, and multiple, white to yellow nodules in the kidneys and small intestine. Histologically, these organs were partially or totally effaced by neoplastic small lymphocytes arranged in sheets, with moderate anisocytosis and anisokaryosis and a low mitotic count. These cells diffusely immunolabeled for CD79α and CD20, and were negative for CD3. A diagnosis of multicentric B-SLL was established and to the authors' knowledge, it has not been previously described in this genus.

Fecal acute phase proteins in cats with chronic enteropathies.

BACKGROUND: Chronic enteropathies (CE) are common in cats and reliable biomarkers that can distinguish different causes and predict or monitor response to treatment are currently lacking. HYPOTHESIS: To evaluate certain acute phase proteins in feces that could potentially be used as biomarkers in cats with CE. ANIMALS: Twenty-eight cats with either inflammatory bowel disease (IBD; n = 13), food-responsive enteropathy (FRE; n = 3) or small cell gastrointestinal lymphoma (SCGL; n = 12) and 29 healthy control cats were prospectively enrolled. METHODS: Fecal concentrations of haptoglobin, alpha-1-acid-glycoprotein (AGP), pancreatitis-associated protein-1 (PAP-1), ceruloplasmin, and C-reactive protein (CRP) were measured using Spatial Proximity Analyte Reagent Capture Luminescence (SPARCL) immunoassays before and after initiation of treatment. Cats were treated with diet and/or prednisolone (IBD cats), plus chlorambucil (SCGL cats). RESULTS: Compared with controls, median fecal AGP concentrations were significantly lower (25.1 vs 1.8 µg/g; P = .003) and median fecal haptoglobin (0.17 vs 0.5 µg/g), PAP-1 (0.04 vs 0.4 µg/g) and ceruloplasmin (0.15 vs 4.2 µg/g) concentrations were significantly higher (P < .001) in cats with CE. Median fecal AGP concentrations were significantly lower (P = .01) in cats with IBD and FRE (0.6 µg/g) compared with cats with SCGL (10.75 µg/g). A significant reduction was found in CE cats after treatment for median fecal ceruloplasmin concentrations (6.36 vs 1.16 µg/g; P = .04). CONCLUSIONS: Fecal AGP concentration shows promise to differentiate cats with SCGL from cats with IBD and FRE. Fecal ceruloplasmin concentrations may be useful to objectively monitor response to treatment in cats with CE.

Splenic Small Cell Lymphoma with Presumed Secondary Immune-Mediated Hemolytic Anemia in an African Penguin (Spheniscus demersus).

A 2-year-old male African penguin (Spheniscus demersus) was presented to a veterinary teaching hospital for evaluation of a previously diagnosed subclinical, marked regenerative anemia. Physical examination at the zoological institution demonstrated biliverdinuria and pale oral mucous membranes. Diagnostic tests performed on the penguin since the diagnosis and prior to presentation to the veterinary teaching hospital included serial complete blood counts, plasma biochemistry panels, radiographic imaging, blood and plasma heavy metal testing, and infectious disease testing. The abnormal diagnostic test results were consistent with marked regenerative anemia and splenomegaly. At the veterinary teaching hospital, further diagnostic testing was ordered in an attempt to determine the cause of the biliverdinuria and pale oral mucous membranes. The diagnostic tests performed included a full-body contrast computed tomographic scan, upper gastrointestinal endoscopic procedure, bone marrow aspiration and evaluation, saline agglutination testing, blood Plasmodium species polymerase chain reaction screening, a vitamin profile panel, and repeat blood heavy metal testing. The complete blood count demonstrated a marked, regenerative anemia with the presence of dysplastic erythrocytes, and splenomegaly was found on the computed tomographic images without identifying a definitive cause. Primary disease differentials for the diagnosed regenerative anemia included a myelodysplastic syndrome and primary or secondary immune-mediated hemolytic anemia. The penguin was treated with oral prednisolone as an immunomodulatory agent; however, it did not result in a positive treatment response. The patient developed hyporexia, weight loss, and lethargy 2 months post presentation to the veterinary teaching hospital. Additional therapy with cyclophosphamide was initiated, and the penguin improved clinically, but then declined. The patient was euthanized due to a poor quality of life and prognosis 4 months after initial presentation and 1.5 years after the first complete blood count revealed the penguin to be anemic. Microscopic review of submitted postmortem tissue samples demonstrated a monomorphic population of neoplastic small lymphocytes infiltrating the spleen, consistent with splenic small cell lymphoma. The neoplastic cells did not label with the T-cell marker CD3 or B-cell markers CD20, CD79a, and Pax-5.

Prognostic value of increased intraepithelial lymphocytes and lymphocytic clonality in dogs with chronic enteropathy or small-cell lymphoma.

The clinical significance of severe infiltration of small intraepithelial lymphocytes (IEL) and the results of polymerase chain reaction for antigen receptor rearrangement (PARR) in dogs with chronic enteropathy (CE) and small-cell lymphoma (SCL) are controversial. This cohort study aimed to evaluate the prognostic significance of the IEL and PARR results in dogs with CE or SCL. Although definitive diagnostic histopathological criteria for SCL in dogs have yet to be established, dogs with the histopathological findings of severe IEL infiltration were diagnosed with SCL in this study. One hundred and nineteen dogs were recruited, with 23 dogs classified as having SCL and 96 dogs as having CE. The positive rate of PARR was 59.6 % (71/119) in the duodenum and 57.7 % (64/111) in the ileum. Subsequently, three dogs with SCL and four dogs with CE developed large-cell lymphoma (LCL). The median overall survival (OS) of dogs with SCL was 700 days (range, 6-1410 days), and that of dogs with CE was not reached. In the log-rank test, shorter OS was observed in cases with histopathological SCL (P = 0.035), clonal TCRγ rearrangement in the duodenum (P = 0.012), and clonal IgH rearrangement in the ileum (P < 0.0001). The Cox proportional hazards model adjusted for sex and age showed that histopathological SCL (hazard ratio [HR] 1.74; 95 % confidence interval [CI], 0.83-3.65), duodenal clonal TCRγ rearrangement (HR, 1.80; 95 % CI, 0.86-3.75), and ileal clonal IgH rearrangement (HR, 2.28; 95 % CI, 0.92-5.70) could shorten overall survival, although their 95 % CIs included 1.0. These results indicate that severe IEL infiltration could be a useful histopathological feature for diagnosing SCL, and clonality-positive results could be a negative prognostic factor in dogs with CE. Furthermore, the development of LCL should be carefully monitored in dogs with CE and SCL..

Concurrent chronic lymphocytic leukemia and primary hyperparathyroidism in a mule.

A 26-year-old mule gelding was evaluated for chronic weight loss and decreased appetite. The mule had been losing weight and intermittently hypophagic for approximately 7 months. Laboratory analysis of whole blood and plasma identified severe total hypercalcemia, marked hypophosphatemia, markedly increased parathyroid hormone concentration, and marked lymphocytosis. A sestimibi scan intended to identify parathyroid gland tissue was nondiagnostic. Results of flow cytometry and PCR for antigen receptor rearrangement (PARR) were consistent with a B cell lymphoproliferative disorder, likely chronic lymphocytic leukemia (CLL). Although not previously described concurrently, these conditions may sometimes arise together, complicating definition of the underlying mechanism for weight loss and hypercalcemia in aged equids.

Detection and Characterization of Paraproteinemia in Canine Chronic B-cell Lymphocytic Leukemia Using Routine and Free Light Chain Immunofixation.

BACKGROUND: Hyperglobulinemia is reported in 26% of canine chronic B-cell lymphocytic leukemia (B-CLL) cases. However, few cases have been characterized by protein electrophoresis and immunofixation (IF), and the incidence of a monoclonal protein (M-protein) is unknown using these techniques. OBJECTIVE: To characterize and determine the proportion of canine B-CLL cases with an M-protein using plasma protein electrophoresis (PPE), routine and free light chain (fLC) IF, and to assess if productive B-CLL cases express MUM1/IRF4 by cell tube block (CTB). METHODS: PPE, routine (targeting IgG, IgA, IgM, IgG4, and light chain) and fLC IF were performed using 48 dog B-CLL plasma samples from patients diagnosed via peripheral blood flow cytometry. CTB was performed on a separate cohort of 15 patients. RESULTS: Hyperproteinemia (>7.5 g/dL) was present in 17/48 cases (35%). An M-protein was detected in 32/48 cases (67%). Of these, 19/32 cases (59%) had only complete (monoclonal heavy and light chain) M-proteins detected, 10/32 cases (31%) had both complete and fLC M-proteins detected, and 3/32 cases (9%) had only an fLC M-protein detected. IgM was the most common clonal immunoglobulin isotype detected (23 cases). CD21+ cell counts were higher in cases with detectable M-protein. Plasma fLC IF suggested ß-γ region interference, likely caused by clotting proteins. All B-CLL cases consistently expressed PAX5 and did not express MUM1/IRF4. CONCLUSIONS: Most B-CLL cases had an M-protein and were not hyperproteinemic. Most cases with paraproteins had a complete IgM monoclonal gammopathy; a subset had documented fLCs. The prognostic significance of heavy and fLC presence should be evaluated.

A case of leukaemia cutis in a dog with T-cell chronic lymphocytic leukaemia.

Leukaemia cutis (LC) is the infiltration of neoplastic leukocytes into the skin, characterised by haemorrhagic papules, nodules, and plaques. LC has been reported in human leukaemia patients, but it is extremely rare in dogs. A 13-year-old spayed female Golden Retriever that was previously diagnosed with chronic lymphocytic leukaemia was managed with chlorambucil (20 mg/m2 orally, every 2 weeks) and prednisolone (2 mg/kg orally, every other day) for 8 months; however, immunosuppression was temporarily discontinued because of a bacterial urinary tract infection. Cutaneous signs, including multifocal ecchymosis and white plaques, appeared 1 month after cessation of chemotherapy. Histopathological examination revealed small- to intermediate-sized lymphocytes with mild atypia in a perivascular to interstitial pattern within the superficial dermis. The bands of atypical cells within the superficial dermis were strongly and extensively positive for CD3 on immunohistochemistry. Polymerase chain reaction analysis of the biopsied skin revealed clonal rearrangement of the T-cell receptor gamma locus gene. Given the evidence of clinical signs, peripheral immunophenotyping, histopathology, immunohistochemistry, and clonal gene arrangement, LC was diagnosed. The lesions disappeared when chemotherapy was restarted but were occasionally observed when chemotherapy was stopped. To the authors' best knowledge, this is the first case report of LC in a dog.

The use of flow cytometry for diagnosis and immunophenotyping in chronic lymphocytic leukemia in a dog: Clinical case report.

Background: Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in dogs. It is characterized by the proliferation of neoplastic lymphocytes in the bone marrow, which are morphologically normal (mature), but non-functional. CLL in canines commonly originates in cytotoxic T lymphocytes (TCD8+), and although there is controversy regarding the prognostic value of the immunophenotype, this cell lineage may be associated with a good prognosis. Case Description: A 10-year-old, entire female, mixed-breed dog was brought to the University Hospital of the Veterinary Faculty (UdelaR) for consultation because a routine pre-surgical check-up revealed lymphocytic leukocytosis, normocytic anemia, and hyperglobulinemia due to an oligoclonal gammopathy. The ultrasound revealed splenomegaly. PCR performed on blood was negative for Ehrlichia canis. Blood and bone marrow flow cytometry was performed to complement the diagnosis and carry out the immunophenotype, which showed CLL of CD8+ T-cell lineage. The clinical suspicion of CLL was confirmed by a myelogram. Chemotherapy treatment based on alkylating agents and glucocorticoids was established. So far, the patient has an overall survival of 13 months with a good response to treatment. Conclusion: The combination of the immunophenotyping test, the myelogram, and the hematological and biochemical profile confirmed the presence of T-CLL in our patient. Flow cytometry, increasingly used in veterinary medicine, allowed us to confirm the diagnosis of CLL originating in cytotoxic T lymphocytes in our patient, through the presence of positive staining of primary antibodies specific for the canine species CD45, CD3, CD5, and CD8 and the absence of staining for CD4, CD21, and CD34.

Chronic Lymphocytic Leukemia in a Cockatiel (Nymphicus hollandicus).

A 24-year-old, female cockatiel (Nymphicus hollandicus) was diagnosed and treated for chronic lymphocytic leukemia. Diagnosis was based on a persistent lymphocytosis, with counts increasing 10 times from reference intervals with a high percentage of well-differentiated lymphocytes in the bone marrow. Immunohistochemical staining confirmed neoplastic cells of T-cell origin. Specific treatment for the disease was initially withheld but commenced based on an increasing lymphocytosis and decreasing packed cell volume. Therapeutic management of the cockatiel's chronic lymphocytic leukemia was based on human protocols. Treatment with chlorambucil stabilized the disease but did not result in a significant regression of the neoplasm. The bird was euthanatized 15 months after the initial diagnosis and 8 months after treatment commenced. On the postmortem examination, extensive T-cell lymphocytic infiltration was found throughout the internal organs.

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.

Clinical outcome and prognostic factors in dogs with B-cell chronic lymphocytic leukemia: A retrospective study.

BACKGROUND: B-cell chronic lymphocytic leukemia (BCLL) in dogs generally is considered an indolent disease, but previous studies indicate a wide range in survival times. OBJECTIVES: We hypothesized that BCLL has a heterogeneous clinical course, similar to chronic lymphocytic leukemia in humans. We aimed to assess presentation and outcome in dogs with BCLL and evaluate the prognostic relevance of clinical and flow cytometric factors. ANIMALS: One hundred and twenty-one dogs with BCLL diagnosed by flow cytometry. Three breed groups were represented: small breed dogs (n = 55) because of increased risk of BCLL; Boxers (n = 33) because of preferential use of unmutated immunoglobulin genes; and other breeds (n = 33). METHODS: Retrospective study reviewing signalment, clinicopathologic data, physical examination findings, treatment, and survival of dogs with BCLL. Cellular proliferation, determined by the percentage of Ki67-expressing CD21+ B-cells by flow cytometry, was measured in 39 of 121 cases. Clinical and laboratory variables were evaluated for association with survival. RESULTS: The median survival time (MST) for all cases was 300 days (range, 1-1644 days). Boxers had significantly shorter survival (MST, 178 days) than non-Boxers (MST, 423 days; P < .0001), and no significant survival difference was found between small breeds and other non-Boxer breeds. Cases with high Ki67 (>40% Ki67-expressing B-cells) had significantly shorter survival (MST, 173 days) than did cases with <40% Ki67 (MST undetermined; P = .03), regardless of breed. Cases with a high lymphocyte count (>60 000 lymphocytes/µL) or clinical signs at presentation had significantly shorter survival. CONCLUSIONS AND CLINICAL IMPORTANCE: B-cell chronic lymphocytic leukemia had a variable clinical course and Boxer dogs and cases with high Ki67 had more aggressive disease.

Serum haptoglobin concentrations in feline inflammatory bowel disease and small-cell alimentary lymphoma: a potential biomarker for feline chronic enteropathies.

OBJECTIVES: The aim of this study was to evaluate serum haptoglobin as a biomarker to differentiate between small-cell alimentary lymphoma and inflammatory bowel disease in cats. METHODS: Client-owned domestic cats with and without chronic gastrointestinal signs were enrolled in the study. Serum was collected from each patient and serum haptoglobin levels were measured using ELISA. In cats with gastrointestinal signs, histopathologic evaluation of endoscopic biopsies harvested from the intestinal tract was used to separate them into inflammatory bowel disease and small-cell lymphoma cohorts. Serum haptoglobin levels were statistically analyzed and compared among the three groups: healthy cats; cats with inflammatory bowel disease; and cats with small-cell alimentary lymphoma. RESULTS: Sixty-two cats were enrolled in the study, including 20 clinically normal cats, 14 cats with small-cell alimentary lymphoma and 28 cats with inflammatory bowel disease. The mean ± SD serum haptoglobin was 73.2 ± 39.1 mg/dl in normal cats, 115.3 ± 72.8 mg/dl in cats with inflammatory bowel disease and 133.1 ± 86.1 mg/dl in cats with small-cell alimentary lymphoma. Cats with inflammatory bowel disease and lymphoma had significantly higher serum haptoglobin than controls, with P values of 0.0382 and 0.0138, respectively. There was no statistical difference between the inflammatory bowel disease and lymphoma cohorts (P = 0.4235). For every one unit increase in serum haptoglobin, the odds of gastrointestinal inflammatory disease (inflammatory bowel disease or small-cell alimentary lymphoma) increased by 1.41% (P = 0.0165). CONCLUSIONS AND RELEVANCE: Serum haptoglobin is a useful biomarker for distinguishing between normal cats and those with gastrointestinal inflammatory disease, but it could not significantly differentiate between inflammatory bowel disease and lymphoma. Additional studies may be beneficial in determining the prognostic significance of serum haptoglobin as it may relate to the severity of gastrointestinal inflammation.

Characterization of the intestinal mucosal proteome in cats with inflammatory bowel disease and alimentary small cell lymphoma.

BACKGROUND: Current tests for diagnosis and differentiation of lymphoplasmacytic enteritis (LPE) and small cell lymphoma (SCL) in cats are expensive, invasive, and lack specificity. The identification of less invasive, more reliable biomarkers would facilitate diagnosis. OBJECTIVES: To characterize the mucosal proteome in endoscopically obtained, small intestinal tissue biopsy specimens. We hypothesized that differentially expressed proteins could be identified and serve as biomarker candidates for the differentiation of LPE and SCL in cats. ANIMALS: Six healthy control cats, 6 cats with LPE, and 8 cats with SCL. METHODS: The mucosal proteome was analyzed using 2-dimensional fluorescence difference gel electrophoresis (2D DIGE) and nanoflow liquid chromatography tandem mass spectrometry. For 5 proteins, results were verified by Western blot analysis. RESULTS: A total of 2349 spots were identified, of which 9 were differentially expressed with a ≥2-fold change between healthy cats and cats with LPE and SCL (.01 < P < .001). Eight of these 9 spots were also differentially expressed between cats with LPE and cats with SCL (P .001 < P < .04). However, Western blot analysis for malate dehydrogenase-1, malate dehydrogenase-2, apolipoprotein, annexin IV, and annexin V did not confirm significant differential protein expression for any of the 5 proteins assessed. CONCLUSIONS AND CLINICAL IMPORTANCE: Two-D DIGE did not identify potential biomarker candidates in the intestinal mucosa of cats with LPE and SCL. Future studies should focus on different techniques to identify biomarker candidates for cats with chronic enteropathies (CE).

Diffuse Small B-Cell Lymphoma: A High-Grade Malignancy.

The most common subtype of lymphoma in the dog is diffuse large B-cell lymphoma (DLBCL). The remaining forms of B-cell lymphoma in dogs are categorized as small-to-intermediate in size and include marginal zone, follicular, mantle cell, and small-cell lymphocytic lymphoma. Marginal zone lymphoma and follicular lymphoma have readily identifiable unique histologic features while other forms of small B-cell lymphoma in the dog are poorly described by histopathology. Forty-seven cases of nodal small B-cell lymphoma identified by flow cytometry (small cell size based on forward scatter) with concurrent histopathology were reviewed. These cases fell into 3 histologic subtypes: marginal zone lymphoma, follicular lymphoma, and a diffuse form of small B-cell lymphoma with consistent features. As a descriptive term, we refer to the latter subtype as diffuse small B-cell lymphoma (DSBCL) until it can be further characterized by gene expression profiling and other molecular tools. Clinical presentation of DSBCL was compared to cases of histologically confirmed DLBCL and clinical follow-up was obtained for 22 of the 27 cases of DSBCL. This subset of diffuse small B-cell lymphoma had an overall median survival of 140 days. The expression of CD21, class II MHC and CD25 by flow cytometry did not differ between DSBCL and the other histologic subtypes of small cell B-cell lymphoma making histopathology the only current method of classification.

Comprehensive comparison of upper and lower endoscopic small intestinal biopsy in cats with chronic enteropathy.

BACKGROUND: Integrating immunohistochemistry (IHC) and clonality testing with histopathology may improve the ability to differentiate inflammatory bowel disease (IBD) and alimentary small cell lymphoma (LSA) in cats. HYPOTHESIS/OBJECTIVES: To evaluate the utility of histopathology, IHC, and clonality testing to differentiate between IBD and LSA and agreement of diagnostic results for endoscopic biopsy (EB) samples from the upper (USI) and lower small intestine (LSI). ANIMALS: Fifty-seven cats with IBD or LSA. METHODS: All cases were categorized as definitive IBD (DefIBD), possible LSA (PossLSA), probable LSA (ProbLSA), or definitive LSA (DefLSA) based on histopathology alone. Results from IHC and clonality testing were integrated. RESULTS: Based on histopathology alone, 24/57 (42.1%), 15/57 (26.3%), and 18/57 (31.6%) cats were diagnosed with DefIBD, PossLSA or ProbLSA, and DefLSA, respectively. After integrating IHC and clonality testing, 11/24 cases (45.8%) and 15/15 cases (100%) previously categorized as DefIBD and PossLSA or ProbLSA, respectively, were reclassified as LSA. A final diagnosis of IBD and LSA was reported in 13/57 (22.8%) and 44/57 (77.2%) cats, respectively. Agreement between USI and LSI samples was moderate based on histopathology alone (κ = 0.66) and after integrating IHC and clonality testing (κ = 0.70). However, only 1/44 (2.3%) of the LSA cases was diagnosed based on LSI biopsy alone. CONCLUSIONS AND CLINICAL IMPORTANCE: Integrating IHC and clonality testing increased the number of cases diagnosed with LSA, but the consequence for patient outcome is unclear. There was moderate agreement between USI and LSI samples. Samples from the LSI rarely changed the diagnosis.

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.