Page 1174 - Cote clinical veterinary advisor dogs and cats 4th

Leukemias, Acute 587

including lymph nodes, nervous system, aleukemic or subleukemic patients, evaluation • Anemia requiring transfusion
kidneys, and GI tract. of the bone marrow is necessary for diagnosis • GI toxicosis
VetBooks.ir DIAGNOSIS ○ Neoplastic cell count ≥ 20% of nucleated Recommended Monitoring Diseases and Disorders
(p. 1068).
• Tumor lysis syndrome
cells in bone marrow is diagnostic for AL.
Diagnostic Overview
nostic information or direct treatment
Immature neoplastic cells on peripheral blood ○ No studies are available to provide prog- • Physical exam and CBC: q 1-2 weeks,
more frequently during induction period;
smears or increased numbers on bone marrow based on bone marrow cytology results. to monitor remission and myelosuppression
smears suggest a diagnosis of AL or stage V ○ Phenotyping is performed on bone • Serum chemistry profile, urinalysis: 1 month
lymphoma. ALL, AML, and lymphoma are marrow aspirates with flow cytom- after starting therapy, then at least q 3-4
typically differentiated by immunophenotyping etry and on core biopsy samples with months: more frequently if indicated
with flow cytometry. In the future, cytogenetic immunohistochemistry.
and molecular genetic/epigenetic analysis will PROGNOSIS & OUTCOME
allow more accurate classification and prognos- TREATMENT
tication of AL. Mutations in genes associated Prognosis is poor for AL. Most patients are ill at
with development of cancer have been identified Treatment Overview diagnosis, and survival times without treatment
in canine ALL and AML. Goal is to eradicate leukemic cells with chemo- are 0-4 weeks. Because ALs are uncommon and
therapy. Supporting the patient until normal many patients are euthanized at diagnosis, there
Differential Diagnosis hematopoiesis resumes is critical. ALL can is limited information describing treatment
• ALL versus AML: it is extremely difficult respond to chemotherapy for short periods; outcomes.
to distinguish ALL from AML based on AML is less responsive. Consultation with a • CD34 (stem cell marker): in dogs, expression
morphology (i.e., cytology). veterinary oncologist is strongly suggested. supports diagnosis of AL; possibly associated
• Available diagnostics do not allow typing of with poorer prognosis (median survival, 16
all ALs. ALs that do not express recognized Acute General Treatment days; range, 3-128 days). CD34 is also
markers are classified as acute undifferentiated • Intensive supportive care is important. expressed in some canine lymphomas.
leukemias (AUL). It is not always possible to ○ Broad-spectrum antibiotic therapy for • ALL: no available prognostic information
distinguish ALL from stage V lymphoma. treating/preventing secondary infections for cats in post-FeLV era. Historically, 65%
• Stage V lymphoma with severe neutropenia (prophylaxis not response rate for median of 7 months. Infor-
• Ehrlichiosis required in cats) mation about prognosis in dogs confounded
○ Intravenous fluid therapy by difficulty distinguishing ALL from stage
Initial Database ○ Peripheral veins for venipuncture/catheter V lymphoma and treatment with a variety
• CBC/blood smear: leukocytosis with blasts placement if severe thrombocytopenia of protocols; 30%-65% respond, with an
and cytopenias. Nonregenerative anemia ○ Transfusions (p. 1169) average survival of days to 4 months. With
and thrombocytopenia common and may ○ Nutritional support CHOP-based protocols, 85% respond, with
be severe. Neutropenia is more common, • Chemotherapy: hospitalization for supportive a remission duration 16-218 days (median,
but neutrophilia is possible. Aleukemic care during induction period is indicated. 41 days).
+
or subleukemic patients have low-normal Clinically significant myelosuppression is ○ CD8 (cytotoxic T-cell) lymphocytosis
white blood cell (WBC) count with no or expected due to myelophthisis. Appropri- (dog): abnormal cell counts > 30,000/
some circulating immature neoplastic cells, ate safety precautions must be taken when mcL associated with shorter survival (131
respectively. handling antineoplastic drugs. vs. 1098 days).*
+
• Flow cytometry is the primary diagnostic ○ Consultation with referral to an oncolo- ○ CD21 (B-cell) lymphocytosis with large
for confirming and classifying AL. Flow gist is recommended due to the need for cells (dog): median survival of 129 days*
cytometry counts and immunophenotypes intensive support, risk of severe adverse ○ This study(*) included dogs with stage V
neoplastic cells. Blood in EDTA should be effects, and for AML, the requirement for lymphoma, CLL, and ALL.
submitted for this test if blasts seen on CBC. intense chemotherapy protocols that are • AML: a few cases surviving 3-4 months have
Because cells must be alive, samples must not routine. been reported. Treatments have minimal
arrive at lab within 24-48 hours. ○ ALL: L-CHOP (L- asparaginase, cyclo- effect on the course of the disease, and
• Polymerase chain reaction (PCR) for antigen phosphamide, hydroxydaunorubicin prognosis is grave.
receptor rearrangement (PARR) identifies [doxorubicin], Oncovin [vincristine],
clonal expression of genes for lymphoid and prednisone)–based chemotherapy PEARLS & CONSIDERATIONS
receptors using blood or bone marrow smears. protocols (p. 602). Radiation has been
A recent study showed AML in dogs is fre- used for central nervous system (CNS) Comments
quently associated with clonal rearrangements involvement; prednisone for palliative care • Cytologic exam of a blood smear is
of lymphoid receptors, so this test is not useful ○ AML: protocols not well defined and imperative if leukocytosis or cytopenias on
for differentiating ALLs from AMLs. results are disappointing. First-line therapy CBC.
• Serum chemistry profile and urinalysis is cytosine arabinoside and doxorubicin; • Patients with AL present with nonspecific
• FeLV/feline immunodeficiency virus ELISA anecdotal responses to L-asparaginase plus signs. Cytologic evaluation of peripheral
test (cats) ± FeLV PCR using bone marrow corticosteroid blood and bone marrow smears diagnoses AL,
(p. 1342). ○ Bone marrow/stem cell transplantation but flow cytometry is needed to differentiate
• Ehrlichia serology, if indicated (p. 285) limited by short remission times and ALL, AML, and stage V lymphoma. Because
• Diagnostic imaging (for staging): thoracic difficulty identifying a suitable donor ALs progress rapidly, consultation with an
radiography, abdominal ultrasonography oncologist should be pursued quickly and
• ± Cytology of enlarged lymph nodes or Chronic Treatment emergency referral considered.
organs: to detect infiltration Patients responding to treatment receive • Owners should be advised of the poor
chemotherapy for the remainder of their lives. prognosis and potential for adverse effects
Advanced or Confirmatory Testing with treatment of AL. Supportive care is
Bone marrow aspiration or core biopsy is used Possible Complications needed.
for evaluation of cell morphology, percentage of • Myelosuppression: neutropenia, thrombo- • Better characterization of AL and develop-
neoplastic cells, and evaluation of cell lines. For cytopenia ment of novel treatments targeting the
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