Cytologic evaluation of primary and secondary myelodysplastic syndromes in the dog

Secondary lymphoma development after chemotherapy in three dogs

Lymphoma is widely recognized in veterinary medicine. However, studies focused on secondary lymphoma after chemotherapy do not exist in veterinary medicine. An 11‐year‐old, spayed female Shih‐Tzu dog was diagnosed with mammary gland carcinoma. Twenty‐five months after carboplatin treatment, the dog developed generalized lymphadenopathy (GL), diagnosed as high‐grade T‐cell lymphoma by immunohistochemistry. Another spayed female Shih‐Tzu dog who was 15‐year‐old had biopsy‐induced gastrointestinal stromal tumour. Three months after being treated with Toceranib, the dog developed GL that was diagnosed by PCR for antigen receptor rearrangement as T‐cell lymphoma. An eight‐year‐old, castrated male Mongrel dog was diagnosed with mast cell tumour. The dog was treated with vinblastine, but 14 months later, GL was revealed. Fine‐needle aspiration indicated lymphoma. The owner declined to investigate the cell lineage. All three dogs developed GL after chemotherapy. We suggest that secondary lymphoma can develop in dogs after chemotherapy for a primary cancer, and thus long‐term follow‐up is necessary.

Clinical and clinicopathological features and outcomes of Miniature Dachshunds with bone marrow disorders

Non-neoplastic bone marrow disorders such as non-regenerative immune-mediated anemia, pure red cell aplasia, and myelodysplastic syndrome are major causes of non-regenerative anemia in dogs. However, there has been no study on the clinical and clinicopathological features of canine non-neoplastic bone marrow disorders in Japan. Hence, we first investigated the breed disposition of non-neoplastic bone marrow disorders that induce anemia as a retrospective study and found that Miniature Dachshund (MD) was a predisposed breed. Based on this finding, we investigated the clinical and clinicopathological features of non-neoplastic bone marrow disorders in MDs as a preliminary retrospective study, and we compared them between immunosuppressive treatment-responsive and -resistant MDs. We found that treatment-resistant MDs showed thrombocytosis and increased frequencies of dysplastic features in the peripheral blood. These results indicate that bone marrow disorders in treatment-resistant MDs might manifest distinct features compared with those in treatment-sensitive MDs, and sensitivity to immunosuppressive treatments could be predicted based on thrombocytosis and dysplastic features in the peripheral blood. Further studies that examine aberrations in the genome are needed to elucidate the pathophysiology of bone marrow disorders in MDs.

The utility of diagnostic tests for immune-mediated hemolytic anemia

BACKGROUND

A definitive diagnosis of immune-mediated hemolytic anemia (IMHA) can be difficult to make. However, it is critical to differentiate IMHA from other causes of anemia due to the impact on prognosis and outcome for IMHA patients. Recently published American College of Veterinary Internal Medicine recommendations for the diagnosis of IMHA should be followed to concurrently confirm ongoing anemia, verify in vivo hemolysis, and detect anti-erythrocyte antibodies. The reliability of immunologic IMHA tests varies depending on which test is used and how it is performed.

OBJECTIVES

Our aims were to determine which tests are currently used in veterinary medicine to diagnose IMHA and review the utility of assays that have historically been used to diagnose IMHA.

METHODS

A short survey was designed to see which diagnostic tests for IMHA were currently being used by veterinary practices. The survey was distributed via list-serves to veterinarians and veterinary technologists. A literature review was performed to report the utility of diagnostic tests for the diagnosis of IMHA.

RESULTS

Survey respondents indicated a variability in test protocols used to diagnose IMHA. Most respondents perform saline agglutination or Coombs' tests to detect anti-erythrocyte antibodies. Additional tests that can be used to support a diagnosis of IMHA are discussed in this review.

CONCLUSIONS

A standardized diagnostic approach should be followed to differentiate IMHA from other causes of anemia. Test methodology can vary from one laboratory to another, and clinicians should be familiar with the procedures used by their laboratory.

Acute Leukemia in Horses

Leukemia is broadly divided into acute and chronic lymphocytic and myeloid types based on the proportion of blasts, morphology of cells, and expression of specific antigens on neoplastic cells. Classifying leukemia in horses can be challenging if blasts predominate and since few antibodies to identify cell types are available. The objective of this study was to describe in detail the clinical and pathologic features of acute leukemia in horses. Twelve horses ranging from 0.2 to 25.9 years of age were diagnosed with acute leukemia. Six cases were classified as acute lymphocytic leukemia (ALL) based on predominance of blasts, lack of granulocytic or monocytic differentiation, and detection of CD3, CD20, and/or CD79a antigens by immunohistochemistry. Six other cases were classified as acute myeloid leukemia (AML) with myelomonocytic ( n = 4), basophilic ( n = 1), and eosinophilic ( n = 1) differentiation based on > 20% bone marrow blasts and partial leukocytic differentiation. Reactivity with antibodies to Iba-1/AIF-1, CD172a, and CD163 was determined for all cases of AML. Eleven horses had thrombocytopenia, 10 had neutropenia, 8 had anemia, all had blasts on blood films, and none had leukocytosis. Ten horses had increased serum acute phase proteins. Bone marrow cellularity ranged from 30% to 100%, and the proportion of blasts ranged from 80% to 100% and 30% to 60% in ALL and AML, respectively. Horses were severely ill at diagnosis and euthanized within days or weeks. Unique features of acute leukemia in horses compared to other species were variable lymphocyte antigen expression (ALL) and frequent inflammation (ALL and AML).

Canine bone marrow cytological examination, classification and reference values: A retrospective study of 295 cases

Cytologic assessment of bone marrow with knowledge of the hemogram represents an effective method to investigate hemic tissue and its function. To determine the spectrum and prevalence of canine bone marrow disorders over a 2 year period in a diagnostic laboratory setting achieved through a standard approach to cytologic bone marrow assessment. A retrospective study of bone marrow fine needle aspirates sample preparations, blood smears, hemogram data and case records. Of the 295 bone marrow samples evaluated, 90 (30.5%) were nondiagnostic samples. Of the remaining samples, 25.1% were classified as hyperplasia of which most were granulocytic hyperplasia (58.1% of the total hyperplasia), 19.3% had no cytological abnormalities, 12.9% had malignant hemopathy and 7.8% had hypo-aplastic conditions. Only a small proportion of cases involved dysplasia (1.7%) and metastatic disease was detected in only one case (0.3%). Reference values of nucleated cells and the M/E ratio were calculated for normal and erythroid and granulocytic hyperplastic bone marrow. This study provides the spectrum and the prevalence of canine bone marrow disorders as well as a differential bone marrow cell counting and determination of reference intervals for diseases.

Alkaline phosphatase is a useful cytochemical marker for the diagnosis of acute myelomonocytic and monocytic leukemia in the dog

BACKGROUND

Immunophenotyping has replaced cytochemical staining as the preferred technique for classifying acute leukemia. However, some acute myeloid leukemias (AML) lack lineage-associated markers. In our experience, alkaline phosphatase (ALP) is expressed in immature canine monocytes. We hypothesized that ALP is a useful marker for monocytic AML.

OBJECTIVES

The objective was to compare ALP expression in neoplastic cells from dogs with lymphoma, chronic lymphocytic leukemia (CLL), acute lymphoid leukemia (ALL), and AML.

METHODS

Alkaline phosphatase results were retrieved from medical records of dogs with acute leukemia. Smears from dogs with lymphoma or leukemia were also prospectively stained for ALP activity. CLL was based on persistent lymphocytosis (10 × 10(9) /L) and acute leukemia on ≥ 20% blasts in blood or bone marrow. ALL was classified based on positive phenotyping for T- or B-lymphocyte antigens, and AML on positive phenotyping for CD11b, CD11c or CD14, or cytochemical staining for chloroacetate esterase, Sudan Black B, or myeloperoxidase.

RESULTS

There was no ALP activity in all 49 lymphomas and 7 CLLs. Weak ALP activity was seen in 31% of 14 ALL (all T-ALL). ALP activity was seen in all 20 AML (P < .001 vs ALL) with strong activity in 64% (vs 25% ALL) in most neoplastic cells (median 75% vs 9% ALL, P = .020). Of AML, 80% were CD34+ (vs 39% ALL, P = .027) and 100% were MHCII- (vs 43% ALL, P = .002).

CONCLUSIONS

ALP activity may be useful for AML confirmation in dogs, particularly if neoplastic cells only express CD34+ on immunophenotyping.

Evaluation of blood and bone marrow in selected canine vector-borne diseases

BACKGROUND

Bone marrow (BM) is a major hematopoietic organ that can harbour a variety of vector-borne pathogens; however, knowledge of BM pathological changes in dogs infected with vector-borne pathogens is limited. Thus, the aim of the present study was to assess the pathological changes in canine BM associated with natural infections by four vector-borne pathogens, as well as to determine the relationships between such changes and abnormalities of the peripheral blood.

METHODS

Cytological disorders and pathological changes of the BM of 83 dogs naturally-infected with one or more of four vector-borne pathogens (i.e., Anaplasma platys, Leishmania infantum, Babesia vogeli and Hepatozoon canis) were evaluated and compared with the corresponding hematological findings.

RESULTS

Dysgranulopoiesis and dysmegakaryocytopoiesis were the most frequently observed BM abnormalities in infected dogs. Erythroid suppression, and lymphocytic, monocytic and macrophage hyperplasia were also observed. Interestingly, associations between suppression and hyperplasia of specific cell lines in the marrow and corresponding changes in numbers of circulating peripheral blood cells were not observed.

CONCLUSIONS

Infections with one or more of the vector-borne pathogens examined in this study should be considered as differential diagnoses for secondary dysmyelopoiesis.

Erythrocyte dysplasia in peripheral blood smears from 5 thrombocytopenic dogs treated with vincristine sulfate

Secondary dyserythropoiesis has been associated with vincristine administration in dogs. Evaluation of bone marrow aspirates for the presence of morphologic abnormalities in the erythroid lineage aids in the diagnosis. However, morphologic features of circulating erythroid precursors in these cases have not been described previously. The purpose of this report was to describe the cytologic features of dyserythropoiesis in peripheral blood and also bone marrow smears in a case series of dogs with immune-mediated thrombocytopenia (IMT) treated with vincristine sulfate. Nineteen dogs receiving vincristine for treatment of IMT were identified by retrospectively searching a computerized medical record system. There were 5 dogs that had dysplastic erythroid precursors in peripheral blood smears within 7 days of vincristine treatment. Two of those 5 dogs also had evidence for erythrodysplasia in modified Wright's-stained bone marrow smears obtained postvincristine administration. Morphologic changes included bizarre or inappropriate mitotic figures, abnormal nuclear configurations (fragmentation, elongation, indentation, and binucleation), atypical nuclear remnants (Howell-Jolly bodies), or nuclear and cytoplasmic asynchrony within the erythroid precursors. A brief review of the literature with discussion of the etiologies for dyserythropoiesis is provided. The dyserythropoiesis was clinically insignificant in all 5 cases and resolved. However, pathologists and clinicians should be aware of these potential findings to prevent misdiagnosis of other conditions.

Cabot rings as a result of severe dyserythropoiesis in a dog

An 11-year-old female Dachshund was presented with depression, diarrhea, weight loss, and radiographic evidence of masses involving the liver, spleen, and cranial lobe of the right lung. Results of a CBC included severe nonregenerative anemia (HCT 14.2%, hemoglobin, 4.3 g/dL, reticulocytes 66,000/microL) with marked metarubricytosis (nucleated RBCs 6.39 x 10(3)/microL). Examination of the peripheral blood smear revealed marked erythroid dysplasia, including marked anisocytosis with a prevalence of macrocytes, Howell-Jolly bodies, diffuse basophilic stippling, and multinucleated and atypical nucleated RBCs. Neutrophil hypersegmentation and giant forms were also noted. Numerous erythrocytes, particularly polychromatophilic cells, contained inclusions consistent with Cabot rings, which appeared as delicate red-purple ellipsoid or figure 8 structures. Rarely, Cabot rings were observed extracellularly. The dog was treated symptomatically with blood transfusions, prednisone, erythropoietin, and vitamin supplementation, but the anemia progressively worsened. The dog was euthanized 2 months after presentation. Bone marrow aspirate and core biopsy specimens obtained at the time of euthanasia revealed marked dysplastic changes in all cell lines, especially dyserythropoiesis, along with infiltrating carcinoma cells. A necropsy was performed, and histologic examination revealed poorly differentiated adenocarcinoma of the lung with multiple metastases to the marrow, spleen, and liver. The final diagnosis was marked myelodysplasia secondary to metastatic adenocarcinoma. Cabot rings are found rarely in humans with myelodysplasia, but have not been described previously in dogs. Based on the findings in this case, Cabot rings may occur rarely in dogs with severe dyserythropoiesis.

A dog with myelodysplastic syndrome: chronic myelomonocytic leukemia

An eleven-year-old female pug was referred to Yamaguchi University Animal Hospital for evaluation of anemia and thrombocytopenia. The cytological examination of the peripheral blood showed some giant monocytic lineage blast cells. A few granulocytes and platelets had dysplastic features. On day 7, in addition to increasing the monocytic lineage cells, the dysplastic features of the blood had also increased compared to the initial examination. We performed bone marrow aspiration upon her death. The bone marrow revealed dysplastic features in all three hematopoietic cell lines, and an increase in the monocytic cell line. Based on the features of the bone marrow and the peripheral blood, this case was confirmed to be myelodysplastic syndrome--Chronic myelomonocytic leukaemia (MDS-CMML).

Evaluation of dysmyelopoiesis in cats: 34 cases (1996–2005)

OBJECTIVE

To further classify dysmyelopoiesis as diagnosed by use of a general classification scheme and to determine clinical features and laboratory test results that could be used to differentiate between the various forms of dysmyelopoiesis in cats.

DESIGN

Retrospective case series. Sample Population-Bone marrow slides from 34 cats.

PROCEDURES

Medical records of cats in which dysmyelopoiesis was diagnosed on the basis of blood and bone marrow analyses from 1996 to 2005 were reviewed. Criteria for inclusion in the study were findings of > 10% dysplastic cells in 1 or more hematologic cell lines in the bone marrow and concurrent cytopenias in the blood. Cats that met these criteria were classified into subcategories of myelodysplastic syndromes or secondary dysmyelopoiesis on the basis of reevaluation of slides.

RESULTS

Of 189 bone marrow slides reviewed, 34 (14.9%) had > 10% dysplastic cells in 1 or more cell lines. Cats were subcategorized as having myelodysplastic syndrome with excessive numbers of blast cells (n = 13), myelodysplastic syndrome with refractory cytopenias (8), a variant form of myelodysplastic syndrome (1), and secondary dysmyelopoiesis (12). Findings of dysmyelopoiesis and autoagglutination in cats with myelodysplastic syndrome and in those with immune-mediated anemia complicated differentiating between the 2 conditions.

CONCLUSIONS AND CLINICAL RELEVANCE

Differentiating cats with myelodysplastic syndromes from cats with immune-mediated hemolytic anemia was difficult because severe anemia and autoagglutination may be concurrent findings in both conditions. Differentiating between myelodysplastic syndrome with excessive numbers of blast cells and myelodysplastic syndrome with refractory cytopenias was useful in predicting clinical outcome.

New insights into the physiology and treatment of acquired myelodysplastic syndromes and aplastic pancytopenia

MDS are a diverse group of primary and secondary bone marrow disorders that are characterized by cytopenias in blood, prominent dysplastic features in blood or bone marrow, and normal or hypercellular bone marrow. MDS in cats are typically associated with FeLV infection. Dogs with MDS-RC and MDS-Er seem to respond to erythropoietin administration and have prolonged survival. Dogs with MDS-EB respond poorly to present treatments, and survival is short. Prognosis and probability of progression to acute myelogenous leukemia can be predicted based on the percentage of myeloblasts in bone marrow. Several experimental therapeutic modalities in human beings have been described that may be useful in treating MDS-EB in dogs and cats. Aplastic pancytopenia is a relatively rare disorder in dogs and cats. Causes include Ehrlichia spp, Parvovirus, and FeLV infections; sepsis; chronic renal failure; drug and toxin exposure; and idiopathic causes. Diagnosis is based on identification of multiple cytopenias in the blood and hypoplastic/aplastic bone marrow, with the marrow space replaced by adipose tissue. Treatment and outcome are dependent on determining the underlying cause of the bone marrow failure.