Hematology: Leukemias

Flashcards for reviewing acute leukemias, including classifications, terminology, and diagnostic methods.

What is the difference between acute and chronic leukemia regarding cell proliferation?

Acute leukemia involves rapid proliferation of immature cells (blasts), while chronic leukemia involves more gradual cell proliferation of mature cells.

What are the typical disease courses for acute and chronic leukemia if left untreated?

Acute leukemia is rapidly fatal (less than 6 months), while chronic leukemia has a more indolent disease course (2-6 years).

Name the two main classifications of leukemia.

Myeloid and Lymphoid.

What is leukemia defined as?

Mutation of pluripotent stem cells that causes impaired production of normal WBCs, RBCs, and platelets, leading to atypical growth and maturation of the cell line.

Define oncogene.

A gene responsible for the development of cancer.

Define cytochemistry.

Staining to differentiate leukemia by enzymes, lipids, or granules.

What does FAB stand for regarding leukemia classification?

French, American, British nomenclature for classification of leukemia.

Define neoplasm.

A proliferation of cells no longer under normal physiologic control (cancer).

Define clonal in the context of leukemia.

Genetically identical direct descendants of a single parent cell.

Give some non-genetic causes of leukemia.

Ionizing radiation, chemical exposure (including chemotherapy), and infectious agents (EBV, HIV, HTLV).

Name some factors that can cause leukemia related to failed oncogenes.

Damage to host genome, decrease DNA repair function, altered ability to detect/destroy developing tumors, and defective immune surveillance.

What are some clinical features of AML (Acute Myelogenous Leukemia)?

Headache, blindness, gum infiltration, joint pain, and heart palpitations.

What is the purpose of cytochemical stains in classifying AMLs?

To identify lipids or enzymes within the blast population and differentiate between myeloid and lymphoid cells.

What does a positive reaction indicate when performing cytochemical stains?

Association with a particular cell lineage.

What does Myeloperoxidase (MPO) stain, and what cells stain strongly positive?

Stains granules; Promyelocytes, myelocytes, metamyelocytes, band and segmented neutrophils will stain strongly positive.

What staining result differentiates ALL from AML when using Myeloperoxidase (MPO)?

Negative reaction differentiates ALL (-) from AML (+).

What does Sudan Black B stain, and how does this differentiate ALL from AML?

Stains phospholipids and other intracellular lipids; Negative in lymphocytes and differentiates ALL (-) from AML (+).

Which cells are strongly positive when using Sudan Black B, and why?

Myeloblasts are strongly positive because the younger cells have more lipids.

What does Specific esterase stain?

Primary granules of young myeloid cells.

Which cells stain positive when using Specific esterase?

Myeloblasts stain positive.

What does Nonspecific esterase stain?

Enzymes in monoblasts.

Which cells are positive when using Nonspecific esterase?

Monocytes and promonocytes will also be positive.

What does Periodic Acid Schiff (PAS) stain?

Glycogen.

Which cells stain positive when using Periodic Acid Schiff (PAS)?

Lymphoblasts and erythroid cells (as in AML M6) stain positive.

What does Leukocyte Alkaline Phosphatase (LAP Score) stain?

Granules in myeloid line.

What does the LAP score indicate in leukemoid reaction and CML?

Score is high in leukemoid reaction and low in CML.

What does Terminal deoxynucleotidyl transferase (TdT) identify?

Intranuclear enzyme found in stem cells and Immature lymphoid cells within the bone marrow.

Which cells will be strongly positive when using Terminal deoxynucleotidyl transferase (TdT)?

Lymphoblasts

What is immunophenotyping used for?

To identify cells using flow cytometry, as each cell type has specific CD markers.

Which nomenclature is used in class for classification?

FAB (French-American-British) nomenclature

Which nomenclature describes the morphology of the predominant cell?

WHO nomenclature

List the classifications of FAB (1976)

M0 -- Undifferentiated AML; M1 -- AML without maturation; M2 -- AML with maturation; M3 -- Acute Promyelocytic Leukemia; M4 -- Acute Meylomonocytic Leukemia; M5 -- Acute Monocytic Leukemia; M6 -- Erythroleukemia (DiGuglielmo's); M7 -- Megakaryoblastic Leukemia

What are Auer Rods (Faggot cell)?

Bundles of auer rods promyelocytes (progranulocytes).

What is M3m?

A variant where the prograns are hypogranular.

What is diagnostic of M3?

Big granules covering cytoplasty and nucleus over rods.

M7-Acute Megalokaryoblastic Leukemia (AMegL)

Uncommon. Platelet peroxidase stain (PPO not MPO) used to identify Megakaryocytic fragments

Epidemiology of ALL

Predominantly disease of children

What percentage of leukemia does ALL account for in children?

Accounts for 76% of all leukemia in children < 13 years old.

How is ALL classified?

ALL is classified by FAB under three subtypes based on the appearance of the predominant blasts

What are the features of Lymphoblasts in ALL-L1?

Lymphoblasts are small with scant cytoplasm, Homogenous-Uniform in size Nucleus regular with rare clefting Absent/Indistinct nucleoli

Name the diagnostic techniques of ALL's.

special stains and Immunophenotyping

In an acute leukemia, the onset of symptoms is what?

quickly happens

The cell maturity in acute leukemias is?

Immature

Acute leukemias affect what age group?

All Age group

What special stains can help us determine if the immature cells are myeloid or lymphoid?

MPO Sudan, ESP