ACUTE MYELOID LEUKEMIAS

14 ACUTE MYELOID LEUKEMIAS



Tarja Juopperi, Heather Leigh DeHeer



1 What are acute myeloid leukemias?


Acute myeloid leukemias (AMLs) are disorders that result from the uninhibited proliferation of a clone of malignant myeloid cells. The neoplastic cell is derived from a hematopoietic stem cell that has the ability to produce cells of the myeloid lineage (erythroid, granulocytic, monocytic, and megakaryocytic). Because lymphocytes are not usually involved in these disorders, AML has also been referred to as acute nonlymphocytic leukemia (ANLL). AMLs are characterized by increased numbers of immature myeloid cells (blasts) in the bone marrow and frequently in the peripheral blood. As the blast cells accumulate within the bone marrow, they replace the normal cellular constituents and often result in peripheral cytopenias (severe anemia, thrombocytopenia).



2 List the clinical signs and physical examination findings that can be seen with AML. What are the related hematologic/cytologic findings?


Animals with AML typically present with a history of nonspecific illness, such as anorexia, weight loss, vomiting, or diarrhea of short duration (days to weeks). Specific clinical signs and physical examination findings may also be seen as a consequence of bone marrow infiltration by leukemic cells (resulting in cytopenias). Abnormal findings may be directly attributable to the hematopoietic cell line that is affected. Table 14-1 lists the clinical signs and physical examination findings frequently seen with animals that have AML and the associated hematologic or cytologic findings.


Table 14-1 Clinical Signs and Physical Examination Findings Attributable to AML































CLINICAL SIGNS/PHYSICAL EXAMINATION HEMATOLOGIC/CYTOLOGIC PATHOPHYSIOLOGY/POSSIBLE CAUSE

Pallor

Lethargy

Weakness
 Anemia
Myelophthisis (decreased production)

Immune-mediated destruction (secondary to neoplasia)
Icterus*  
Maturation arrest of precursors

Hemorrhage (if thrombocytopenia also present)

Persistent/recurrent fever

Infections
 Neutropenia
Myelophthisis

Functional defects in neutrophils

Epistaxis

Petechiae/ecchymoses
 Thrombocytopenia Disseminated intravascular coagulation

Hemorrhage

Lameness, hemarthrosis
  
Splenic sequestration

Myelophthisis

Platelet dysfunction

Splenomegaly

Hepatomegaly

Lymphadenopathy (mild)

Bone pain (lameness)

Icterus†
 Increased numbers of blasts (cytology) Infiltration by leukemic cells

* As a result of hemolysis.


† As a result of hepatic infiltration.



3 What are the potential peripheral blood findings in an animal with AML?


The hematologic features of AML are diverse, and animals may exhibit a wide range of peripheral blood findings. Hematologic abnormalities vary depending on the subtype of AML present, but cytopenias (anemia and thrombocytopenia) are the most frequent findings. Total leukocyte and blast cell counts are unpredictable, ranging from decreased to within normal range to greatly elevated (leukocytosis is more common). Table 14-2 lists potential peripheral blood findings in an animal with AML.


Table 14-2 Possible Peripheral Blood Findings in Animal with AML









CELL TYPE PERIPHERAL BLOOD FINDINGS
Erythrocytes
Anemia* (severe, nonregenerative)

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Aug 26, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on ACUTE MYELOID LEUKEMIAS

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