1.6 - Acute Leukemias

Auer rods may be seen in all of the following except:

A. Acute myelomonocytic leukemia (M4)

B. Acute lymphoblastic leukemia (ALL)

C. Acute myeloid leukemia without maturation (AML:M1)

D. Acute promyelocytic leukemia (PML:M3)

B. Acute lymphoblastic leukemia (ALL)

Which type of anemia is usually present in a patient with acute leukemia?

A. Microcytic, hyperchromic

B. Microcytic, hypochromic

C. Normocytic, normochromic

D. Macrocytic, normochromic

C. Normocytic, normochromic

• In acute leukemia, the bone marrow is infiltrated with blasts, which suppress normal hematopoiesis.

• This results in a normocytic, normochromic anemia due to marrow replacement and decreased RBC production, rather than a defect in hemoglobin synthesis or cell maturation.

In leukemia, which term describes the peripheral blood finding of leukocytosis with a shift to the left, accompanied by NRBCs?

A. Myelophthisis

B. Dysplasia

C. Leukoerythroblastosis

D. Megaloblastosis

C. Leukoerythroblastosis

The basic pathophysiological mechanisms responsible for producing signs and symptoms in leukemia include all of the following except:

A. Replacement of normal marrow precursors by leukemic cells causing anemia

B. Decrease in functional leukocytes causing infection

C. Hemorrhage secondary to thrombocytopenia

D. Decreased erythropoietin production

D. Decreased erythropoietin production

Which type of acute myeloid leukemia is called the "true monocytes leukemia" and follows an acute or subacute course characterized by monoblasts, promonocytes, and monocytes?

A. Acute myeloid leukemia, minimally differentiated

B. Acute myeloid leukemia, without maturation

C. Acute myelomonocytic leukemia

D. Acute monocytic leukemia

D. Acute monocytic leukemia

In which age group does ALL occur with the highest frequency?

A. 1 - 15 years

B. 20 - 35 years

C. 45 - 60 years

D. 60 - 75 years

A. 1 - 15 years

Disseminated intravascular coagulation (DIC) is most often associated with which of the following types of acute leukemia?

A. Acute myeloid leukemia, without maturation

B. Acute promyelocytic leukemia (PML)

C. Acute myelomonocytic leukemia

D. Acute monocytic leukemia

B. Acute promyelocytic leukemia (PML)

An M:E ratio of 10:1 is most often seen in:

A. Thalassemia

B. Leukemia

C. Polycythemia Vera (PV)

D. Myelofibrosis

B. Leukemia

Which of the following is a characteristic of Auer rods?

A. They are composed of azurophilic granules

B. They stain positive on periodic acid-Schiff (PAS) staining

C. They are predominantly seen in chromic myelogenous leukemia (CML)

D. They are nonspecific esterase positive

A. They are composed of azurophilic granules

The following laboratory values are seen:

WBC = 6.0 x 10^9/L, RBC = 1.90 x 10^12/L, PLT = 130 x 10^9/L, Hgb = 6.0 g/dL, Hct = 18.5%

Serum vitamin B12 and folic acid: normal

WBC Differential:

6% PMNs, 40% lymphocytes, 4% monocytes, 50% blasts

Bone Marrow:

40% myeloblasts, 60% promegaloblasts, 40 megaloblastoid NRBCs/100 WBCs

These results are most characteristic of:

A. Pernicious anemia

B. Acute myeloid leukemia, without maturation

C. Acute erythroid leukemia

D. Acute myelomonocytic leukemia

C. Acute erythroid leukemia

• The bone marrow shows a predominance of erythroid precursors (megaloblastoid NRBCs) along with myeloblasts, a pattern characteristic of acute erythroid leukemia (formerly FAB M6).

• Normal vitamin B₁₂ and folate exclude megaloblastic anemia, and the presence of >50% erythroid precursors among nucleated cells with significant dysplasia confirms an erythroid lineage malignancy, not a purely myeloid process.

A 24-year-old man with Down syndrome presents with fever, pallor, lymphadenopathy, and hepatosplenomegaly. His CBC results are as follows:

WBC = 10.8 x 10^9/L, 8% PMNs, 25% lymphocytes, 67% PAS-positive blasts

RBC = 1.56 x 10^12/L, Hgb = 3.3 g/dL, Hct = 11%, PLT = 2.5 x 10^9/L

These findings are suggestive of:

A. Hodgkin lymphoma

B. Myeloproliferative disorder

C. Leukemoid reaction

D. Acute lymphocytic leukemia

D. Acute lymphocytic leukemia

• The patient’s young age, Down syndrome association, and presence of PAS-positive blasts (a hallmark of lymphoblasts) strongly indicate acute lymphoblastic leukemia.

• The findings of severe anemia, thrombocytopenia, lymphadenopathy, and hepatosplenomegaly further support marrow infiltration by lymphoid blasts rather than a reactive or myeloid process.

A peripheral blood smear shows 75% blasts. These stain positive for both Sudan Black B (SBB) and peroxidase. Given these values, which of the following disorders is most likely?

A. Acute myelocytic leukemia (AML)

B. CML

C. Acute undifferentiated leukemia (AUL)

D. ALL

A. Acute myelocytic leukemia (AML)

• Sudan Black B (SBB) and myeloperoxidase (MPO) stains are positive in myeloid blasts but negative in lymphoid blasts, helping distinguish AML from ALL.

• A smear with ≥20% blasts that are SBB and MPO positive is diagnostic of a myeloid lineage leukemia, confirming acute myelocytic leukemia.

In myeloid cells, the stain that selectively identifies phospholipid in the membranes of both primary and secondary granules is:

A. PAS

B. Myeloperoxidase

C. SBB

D. Terminal deoxynucleotidyl transferase (TdT)

C. SBB

• Sudan Black B stains phospholipids, neutral fats, and sterols present in the primary (azurophilic) and secondary (specific) granules of myeloid cells.

• It parallels myeloperoxidase (MPO) in identifying myeloid lineage, but it’s based on lipid solubility rather than enzymatic activity.

Sodium fluoride may be added to the naphthyl ASD acetate (NASDA) esterase reaction. The fluoride is added to inhibit a positive reaction with:

A. Megakaryocytes

B. Monocytes

C. Erythrocytes

D. Granulocytes

B. Monocytes

• Sodium fluoride specifically inhibits the nonspecific esterase activity of monocytes, distinguishing them from granulocytes, which remain positive in the NASDA esterase (nonspecific esterase) stain.

• This property helps differentiate monocytic leukemias (inhibited) from granulocytic leukemias (not inhibited) during cytochemical classification.

Leukemic lymphoblasts reacting with anti-common acute lymphoblastic leukemia antigen (anti-CALLA) are characteristically seen in:

A. B-cell ALL

B. T-cell ALL

C. Null-cell ALL

D. Common ALL

D. Common ALL

• Common acute lymphoblastic leukemia (ALL) is defined immunologically by the presence of CALLA (CD10) on the surface of precursor B lymphoblasts.

• These blasts are TdT-positive, HLA-DR-positive, and typically negative for surface Ig, distinguishing common ALLfrom T-cell and mature B-cell (Burkitt-type) ALL.

Which of the following reactions are often positive in ALL but are negative in AML?

A. TdT and PAS

B. Chloroacetate esterase and nonspecific esterase

C. SBB and peroxidase

D. New methylene blue and acid phosphatase

A. TdT and PAS

A patient's peripheral blood smear and bone marrow both show 70% blasts. These cells are negative on SBB staining. Given these data, which of the following is the most likely diagnosis?

A. AML

B. Chronic lymphocytic leukemia

C. Acute PML

D. ALL

D. ALL

Which of the following leukemias are included in the 2008 World Health Organization classification of myeloproliferative neoplasms (MPN)?

A. CML

B. Chronic neutrophilia leukemia (CNL)

C. Chronic eosinophilic leukemia (CEL)

D. All of these options are classified as MPN

D. All of these options are classified as MPN

In addition to morphology, cytochemistry, and immunophenotyping, the WHO classification of myelo- and lymphoproliferative disorders is based on which characteristic?

A. Proteomics

B. Cytogenetic abnormalities

C. Carbohydrate-associated tumor antigen production

D. Cell signaling and adhesion markers

B. Cytogenetic abnormalities

The WHO classification requires what percentage for the blast count in blood or bone marrow for the diagnosis of AML?

A. At least 30%

B. At least 20%

C. At least 10%

D. Any percentage

B. At least 20%

What would be the most likely designation by the WHO for AML M2 by the FAB classification?

A. AML with t(15;17)

B. AML with mixed lineage

C. AML with t(8;21)

D. AML with inv(16)

C. AML with t(8;21)

• In the FAB system, AML M2 refers to acute myeloblastic leukemia with maturation, which under the WHO classification corresponds to “AML with t(8;21)(q22;q22); RUNX1-RUNX1T1.”

• This translocation is associated with myeloblasts showing maturation, Auer rods, and often eosinophilic cytoplasmic granules, and it generally carries a favorable prognosis.

What would be the most likely designation by the WHO for AML M3 by the FAB classification?

A. AML with t(15;17)

B. AML with mixed lineage

C. AML with t(8;21)

D. AML with inv(16)

A. AML with t(15;17)

• FAB M3 corresponds to acute promyelocytic leukemia (APL), which under the WHO classification is designated “AML with t(15;17)(q22;q12); PML-RARA.”

• This translocation fuses the PML and RARA genes, blocking myeloid maturation at the promyelocyte stage and predisposing to DIC; it responds characteristically to all-trans retinoic acid (ATRA) therapy.

Which AML cytogenetic abnormality is associated with AML M4 with marrow eosinophilia under the WHO classification of AML with recurrent genetic abnormalities?

A. AML with t(15;17)

B. AML with mixed lineage

C. AML with t(8;21)

D. AML with inv(16)

D. AML with inv(16)

• AML M4 with eosinophilia (FAB M4Eo) corresponds to “AML with inv(16)(p13q22) or t(16;16)(p13;q22); CBFB-MYH11” under the WHO classification.

• This abnormality disrupts the core-binding factor (CBF) complex, leading to myelomonocytic blasts with abnormal eosinophils containing large basophilic granules, and it is typically associated with a favorable prognosis.

What would be the most likely classification by the WHO for AML M7 by the FAB classification?

A. Acute myeloid leukemias with recurrent genetic abnormalities

B. Acute myeloid leukemia with multi-lineage dysplasia

C. Acute megakaryoblastic leukemia classified under AML (not otherwise categorized)

D. Acute leukemias of ambiguous lineage

C. Acute megakaryoblastic leukemia classified under AML (not otherwise categorized)