MLAB 1315 Hematology Keri BrophyMartinez

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MLAB 1315- HematologyKeri Brophy-Martinez

• Unit 20 Introduction to Leukemia and the Acute
  Leukemias

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• Leukemia is a malignant disease of hematopoietic
  tissue characterized by replacement of normal
  bone marrow elements with abnormal (neoplastic)
  blood cells.

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Classification of leukemia

• According to cell type with regard to both cell
  maturity and cell lineage.
• Chronic
• More mature cells
• Usually occurs in adults
• Clinical onset is gradual
• Anemia and thrombocytopenia are mild
• WBC is increased
• Organomegaly is prominent

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• Acute
• Immature cells
• Occurs in all ages
• Clinical onset is sudden
• Anemia and thrombocytopenia are mild to severe
• WBC is variable
• Organomegaly is mild

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Cell lineage

• Lymphoid
• Myeloid

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Four broad categories

• Acute lymphoblastic (ALL)
• B-cell
• T-cell
• Acute myeloid (AML) or acute non-lymphoblastic
  (ANLL)
• Acute myeloid
• Acute promyelocytic
• Acute myelomonocytic
• Acute monocytic
• Erythroleukemia
• Megakaryocytic

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• Chronic lymphocytic (CLL)
• Chronic myelocytic (CML) - also called Chronic
  Granulocytic (CGL)

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Risk factors for leukemia

• Host factors
• Hereditary
• families with leukemia have an increased
  predisposition
• Congenital chromosome abnormalities
• Fanconis anemia
• Downs syndrome (18-20 fold increased incidence)
• Immunodeficiency
• Ataxia-telangiectasia - lymphoid leukemia or
  lymphoma
• Sex-linked agammaglobulinemia

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Risk factors cont

• Chronic marrow dysfunction
• Myelodysplastic syndrome
• Polycythemia vera
• Aplastic anemia
• Paroxysmal nocturnal hemoglobinurea (PNH)

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Environmental factors

• Ionizing radiation
• Nuclear weapons
• Chemicals and drugs
• Benzene
• Chloramphenicol, phenylbutazone
• Certain chemotherapy drugs that are cytotoxic,
  especially when used in conjuction with
  therapeutic radiation
• Viruses
• HTLV-I
• HTLV-II
• Epstein-Barr virus

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Acute leukemia

• Clinical features
• Weakness - caused by anemia
• Bleeding abnormalities - caused by
  thrombocytopenia
• Flu-like symptoms - joint and body pain caused by
  expanding mass of the marrow or organomegaly
• Nausea, vomiting - caused by infiltration of
  leukemic cells in the central nervous system
  (CNS)

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Differentiation between AML and ALL

• Age
• AML - mainly in adults
• ALL - common in children
• Blood
• AML - anemia, neutropenia, thrombocytopenia,
  myeloblasts and promyelocytes
• ALL - anemia, neutropenia, thrombocytopenia,
  lymphoblasts and prolymphocytes
• Morphology
• AML - blasts are medium to large with more
  cytoplasm which may contain granules, Auer rods,
  fine nuclear chromatin, distinct nucleoli
• ALL - blasts are small to medium with scarce
  cytoplasm, no granules, fine nuclear chromatin
  and indistinct nucleoli
• Cytochemistry
• AML - positive peroxidase and Sudan black,
  negative TdT
• ALL - negative peroxidase and Sudan black,
  positive TdT

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Cytochemical stains

• Evaluation of positivity in these stains must be
  determined on the leukemic blast stage of the
  cell
• Types
• Myeloperoxidase
• Activity is present in the primary granules and
  Auer rods of myeloid cells
• Stains late myeloblasts, granulocytes, monocytes
  less intensely
• Differentiates AML from ALL
• Granules stain red
• Smears must be fresh

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Cytochemical stains cont

• Sudan Black B
• Activity is present in phospholipids in the
  membrane of 1 and 2 granules
• Parallels myeloperoxidase but smears do not have
  to be fresh
• Granules stain black
• Specific Esterase (Naphthol AS-D Chloroacetate)
• Activity is in cytoplasm
• Stains neutrophilic granulocytes
• Parallels myeloperoxidase
• Granules stain blue-black

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Cytochemical stains cont

• Nonspecific Esterase (Alpha-Naphthyl Acetate)
• Activity is in cytoplasm
• Stains monocytes and also megakaryocytes
• Differentiates myeloblasts from monoblasts (can
  use a double staining technique to view both
  specific and nonspecific stains on one smear)
• Addition of Na fluoride to this stain inhibits
  activity in monocytes
• Granules stain orange red

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Cytochemical stains cont

• Periodic Acid Schiff (PAS)
• Activity is in glycogen and related substances
• Stains lymphocytes, granulocytes, megakaryocytes
• Helpful in diagnosing erythroleukemia where there
  is strong reactivity in normoblasts
• Stains red-purple in blocks in cytoplasm

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Diagnostic tests

• Immunologic marker studies
• Cell surface markers
• Monoclonal or polyclonal antisera is added to
  cell suspensions of fresh peripheral blood or
  bone marrow and an immunofluorescent method is
  used in a flow cytometry instrument to analyze
  the markers which are expressed as cluster
  designations (CD). CDs identify antibodies that
  are specific for certain cells and allow for a
  positive identification.
• Cytoplasmic immunoglobulin
• Used to detect pre-B cells which contain the µ
  heavy chain.
• Terminal Deoxynucleotidyl Transferase (TdT)
• TDT is a unique nuclear enzyme present in stem
  cells and precursor of B- and T ymphoid cells.
  It is present in most cases of lymphoblastic
  lymphoma and about ? of CML in blast crisis.
  (CML-BC)

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Diagnostic tests cont

• Molecular Genetics
• This newer method of diagnosing leukemia consists
  of DNA probes and polymerase chain reaction
  (PCR)-based studies. They are rapid and precise
  and are used to confirm chromosomal abnormalities
  that are not detected by conventional studies.
  They are also used to monitor residual disease
  following therapy.
• Cytogenetics (Chromosome studies)
• Identifies chromosome translocations which are
  specific for certain leukemias
• Philadelphia chromosome (t922) is associated
  with CML
• t1517 is associated with acute promyelocytic
  leukemia

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Treatment of acute leukemia

• Cures are not common except in childhood
  leukemia. The best hope for a cure in adults
  lies in bone marrow transplantation.
• Cytoreductive chemotherapy
• Reduces the leukemic cell mass
• Block DNA synthesis
• Block RNA synthesis
• Complications arise from marrow hypoplasia and
  resulting cytopenia

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Treatment of acute leukemia cont

• Radiotherapy (radiation)
• Kills focalized leukemic cells
• Usually used in addition to chemotherapy and for
  CNS prophylaxis
• Bone marrow transplantation
• Bone marrow is eradicated with chemo and
  radiation.
• Compatible donor cells are transfused and they
  travel to the empty marrow where they engraft and
  repopulate the marrow with healthy cells.
• Complications include graft vs host (GVH) disease
  which can be fatal.

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Acute Myeloid Leukemia

• FAB (French, American, British) classification
• Based on morphological characteristic of
  Wright-stained cells in peripheral blood or bone
  marrow with supplementary cytochemical stains

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Classification

• M0
• Myeloid without morphological maturation
• No cytochemical maturation
• M1
• Blasts and promyelocytes predominate without
  further maturation
• Minimal cytochemical maturation
• Auer rods are seen in cytoplasm of blasts.
• Auer rods are a rod-shaped alignment of primary
  granules that are present only in the cytoplasm
  of myeloblasts and monoblasts in leukemic states.
  They stain red with Wrights stain.

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Classification cont

• M2
• Myelogenous cells demonstrate maturation beyond
  the blast and promyelocyte stage
• M3
• Promyelocytic
• Often present with disseminated intravascular
  coagulation (DIC) caused by promyelocytes which
  are rich in thromboplastic substances that
  initiate clotting. Heparin therapy is initiated
  prior to chemotherapy.
• Promyeloblasts may contain faggot cells which
  contain bundles of Auer rods in the cytoplasm.
• t(1517) chromosomal translocation

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Classification cont

• M4
• Myelomonocytic
• Blasts contain folded nuclei and moderate to
  abundant cytoplasm
• Increased serum lysozyme level
• M5
• Monocytic (well and poorly differentiated)
• Monoblasts migrate to extramedullary sites such
  as the skin and gums causing hypertrophy.
• Peripheral blood may have increased monocytes.

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Classification cont

• M6
• Erythroid (also called DiGuglielmos disease)
• Bone marrow is hypercellular with marked
  erythroid hyperplasia.
• Megaloblastoid changes in erythrocytes including
  bizarre multinucleation, vacuolated cytoplasm and
  cytoplasmic budding.
• M7
• Megakaryoblastic
• Uncommon
• Peripheral blood may contain micromegakaryoblasts.
  
• Marrow may be fibrosed

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Acute Lymphoblastic Leukemia

• This type of leukemia is predominant in children
  aged 2-10 years. Differentiation is done by
  morphology on bone marrow blasts, surface marker
  analysis and TdT analysis

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ALL FAB Classification

• L1 Small, uniform lymphoblasts
• L2 Large, pleomorphic lymphoblasts
• L3 Burkitts type (vacuolated and deeply
  basophilic)