Introduction to Leukemias 2022 St. PDF

Introduction to Leukemias MDLS 4226/5226 Hematology II Objectives In accordance with MLS student guidelines, at the completion of this lecture the student is expected to use the information gained to correctly:  Analyze the term “leukemia”  Contrast Acute and Chronic Leukemias in regards to path...

Introduction to Leukemias MDLS 4226/5226 Hematology II Objectives In accordance with MLS student guidelines, at the completion of this lecture the student is expected to use the information gained to correctly:  Analyze the term “leukemia”  Contrast Acute and Chronic Leukemias in regards to pathophysiology, cellular populations, clinical presentations, and prognosis.  Examine the classification schemas for leukemia  Evaluate the four methodologies used to classify and identify leukemias  Explain the etiology of leukemias Objectives        Appraise the laboratory evaluation, limitations, and role of pathologists in the working of leukemias Compare and contrast the five different types of leukemia treatment Differentiate between syngeneic, allogeneic, and autologous bone marrow transplants Compare leukemoid reactions and leukoerythroblastic reactions Evaluate the methodology and grading of LAP stains Correlate LAP results with corresponding clinical significance Predict the identification of cells and corresponding clinical disorders presented in this lecture, using patient history and/or clinical laboratory results. Background Leukemia = progressive, malignant disease of hematopoietic system  Characterized by unregulated proliferation of (usually) 1 cell line  Abnormal cells originate in bone marrow & then spread into peripheral blood Leukemias are grouped by cell lineage and by the maturity of affected cells (acute or chronic)  Cause of malignancy is usually unknown (a few exceptions)  Not localized, but are systemic in nature Most treatment options are systemic as well Acute Leukemia Characterized by:  Preponderance of immature cells. You see a gap in N. maturation process in bone marrow The N. "pyramid" of cell development instead has many blasts, some mature forms, & a few intermediate stages = leukemic hiatus.  Sudden onset  Short, aggressive disease pattern  Lots of infections & hemorrhaging  FAB defines by > 30% blasts in bone marrow  WHO defines by > 20% blasts in bone marrow (- blastic) Chronic Leukemia Characterized by:  All stages of maturation seen, with predominantly mature cells.  Insidious onset  Lengthier, less aggressive disease pattern (lots of organ infiltration & massive leukocytosis).  FAB defines by < 30% blasts in bone marrow  WHO defines by < 20% blasts in bone marrow (- cytic) NOTE: Chronic som etim es turns into acute! Called "blast crisis". Acute vs. Chronic Leukemia Acute Leukemia Chronic Leukemia Onset Abrupt Insidious Death Months Years Patient’s Age All ages Adults WBC Count Variable (can be very low!) High Cell Maturity Immature Mature Plt. Count Variable (can be very low!) N. to Increased Organomegaly Mild Severe Classification schemas for Leukemias     Up until 1947, it didn’t matter what you called a leukemia, because there was no therapy for them! FAB (French-American-British) system established in 1976 to provide uniform criteria for classifying acute leukemias before treatment changed their cellular morphology FAB also wanted to aid in correlating treatment response to outcome, & to eventual prognosis. Based on cell lineage and cytochemical response   Goal was to distinguish lymphoid from myeloid leukemias Worked ok for differentiating the basic acute vs. chronic and lymphocytic vs. myeloid, but… Classification schemas for Leukemias   Massive information explosion, along with advent of advanced techniques, caused World Health Organization (WHO) to develop modified FAB system in 2001 – updated in 2008 and 2016. WHO emphasized correlation of cytogenetic & immunochemistry studies with specific leukemia subtypes AND with clinical outcomes, in order to finetune treatment modalities.  FYI: FAB has difficulty classifying plt. disorders, lymphoproliferative disorders, & variant monoblastic presentations. Four Methodologies Used for Identifying & Classifying Leukemias: 1a. Morphologic review of bone marrow  Historically most used, but really inadequate except for differentiating acute vs. chronic! Cannot really be used by itself! 1b. Morphologic review of peripheral blood smears  What we use in lab, but of limited diagnostic utility. Cannot ever be used by itself – send out for path review. Four Methodologies Used for Identifying & Classifying Leukemias: 2. Cytochemical stains (Ex., NSE, LAP, etc.)    Historically very useful. Identifies specific molecules in malignant cells (Ex., lipids, enzymes) that are associated with specific cell lines. Giving way to immunophenotyping & cytogenetic analyses . . Four Methodologies Used for Identifying & Classifying Leukemias: 3. Immunophenotyping  Via fluorescent Abs  Used for specific cell lineage &/or specific maturation stage markers.  FYI: For example, ↓ expression ABO antigens common in leukemias.  Done by flow cytometry (very good for acute leukemias) using 5-color immunofluorescence. (Markers may be surface, cytoplasmic, or nuclear.)  Examples . . . Four Methodologies Used for Identifying & Classifying Leukemias: 3. Immunophenotyping (cont.)  Flow cytometry marker examples:    Surface marker Ags/receptors – CD, HLA, etc. Certain cell surface Ags associated with specific tumor phenotypes. Cytoplasmic Nuclear a. Enzymes - Terminal deoxynucleotidyl Transferase (TdT) = unique enzyme present only in early lymphoid cells. Thus ↑ levels seen in lymphoblastic leukemias (ALL), but not typically seen in AMLs (?) Acute myelocytic / myelogenous / myeloid / myeloblastic / nonlymphocytic b. Aneuploidy – if tumor is aneuploid, ↑ aneuploidy = ↑ risk of relapse Four Methodologies Used for Identifying & Classifying Leukemias: 4. Cytogenetic & molecular analyses – the “Supreme Court of Diagnosis”, using: a. Karyotyping – microscopic whole chromosome analysis. b. FISH (Fluorescence In Situ Hybridization) – can use any sample type. FYI: Excellent for micro-deletion syndromes (caused by mismatch during crossing over.) (Ex., some ą-thalassemias, DiGeorge Syndrome) c. PCR – yields quantitative results; old favorite technique. Normal gene rearrangement = NO (malignancy); Positive translocation = YES (malignancy) “Molecular remission” = PCR negative Result is 4 Major Types of Leukemia: 1. ALL - Acute Lymphoblastic (less specifically, Lymphocytic) Leukemia 2. CLL - Chronic Lymphocytic Leukemia 3. AML - Acute Myeloblastic (less specifically, Myelocytic or Myeloid) Leukemia; aka. ANLL (Acute Nonlymphocytic Leukemia) 4. CML - Chronic Myelocytic / Myelogenous / Myeloid Leukemia Detailed List, Four Major Leukemia Groups: ACUTE CHRONIC Myeloid (AML) Lymphoid (ALL) Myeloid Lymphoid Myelocytic/ Myelogenous T lymphocytic Myelocytic/ Myelogenous (CML) Lymphocytic (CLL) Promyelocytic B lymphocytic Myelomonocytic (CMML) Plasmacytic Monocytic Null Cell (?) Myelomonocytic (AMML) Erythrocytic (AEL) Megakaryocytic (AMegL) Hairy Cell (HCL) Prolymphocytic (PLL) Etiology For most, the cause of malignancy is unknown…but there are a few exceptions 1. Genetics – hundreds of genetic defects now known to cause cancers. Usually somatic translocations & aneuploidy 2. Leukemogens - chemicals causing bone marrow depression & aplasia predispose to leukemia later on (Ex., benzene, chloramphenicol, sulfa drugs, insecticides, antineoplastics) 3. Viral infections - some retroviruses transform N. cells by inserting their own oncogenes into host cell's genome, causing them to become malignant. [EBV linked to Burkitt non-Hodgkin lymphoma] 4. Radiation Chromosomal Abnormalities   Proto-oncogenes are normal genes which become altered by mutation to become oncogenes. Oncogenes – genes that cause cancer mutations.   Mutated version of a proto-oncogene Ex: CML t(9;22) and Burkitt Lymphoma t(8;14)     CML: ABL proto-oncogene on chromosome 9 is activated when fused with the BCR component of chromosome 22 Burkitt Lymphoma: MYC proto-oncogene on chromosome 8 is activated when fused with Ig on chromosome 14 Aneuploid – a chromosome number that is abnormal. Tumor suppressor genes code for proteins which resist malignancy. Laboratory Evaluation A. Preliminary Workup of peripheral blood:     CBC with plts. and diff. RBCs – have normo-, normo- anemia (usually). Typically this is myelophthisic anemia (?) hypoproliferative bone marrow due to replacement of hematopoietic tissue by leukemic cells Plt. & WBC counts – variable: mkd. ↓ in acute, ↑ in acute or chronic, to mkd. ↑ in chronic. Diff. - usually see blasts & immature forms… if acute, numerous mature forms if chronic. Laboratory Evaluation B. Second Stage Workup: bone marrow aspirate & biopsy analysis: 30 % blasts in bone marrow required  Minimum ___ for acute diagnosis in FAB system  Minimum ___ 20 % blasts in bone marrow required for acute diagnosis in WHO system  stains Cytochemistry – using ? special _____________  Immunophenotyping – using ? Abs & fluorescent stains Laboratory Evaluation B. Second Stage Workup: bone marrow aspirate & biopsy analysis:  Cytogenetic studies – using what techniques? PCR & FISH Also used to detect Minimal Residual Disease (MRD) – the lowest level of disease detectable in pts. who are in continuous clinical remission . . . FYI: Method Sensitivity to Levels of Tumor Burden METHODOLOGY       Clinical Symptoms CBC Cytogenetic Assays FISH assays Flow cytometry PCR assays SENSITIVITY grossly visible microscopically visible 95% 99.5% 99.9% 99.99% Treatment The best therapy must start with an accurate diagnosis Two main goals of leukemia treatment: 1. Eradicate leukemic cell mass. 2. Provide supportive care for symptoms. Factors playing roles in prognosis & treatment modalities are the pt.'s:     Pretreatment health status Age Concurrent infection(s) Abnormal cytogenetics FYI: The younger the patient & the less symptomatic, the greater the response to therapy likely will be. Treatment Categories of therapy: 1. 2. 3. 4. 5. chemotherapy radiation therapy supportive therapy targeted therapy stem cell transplantation Treatment 1. Chemotherapy   Typically given IV in conjunction with antibiotics; for diffuse malignancies. Drugs can be classified by their effects on the cell cycle and by their biochemical mechanism of action. Some affect specific phases of the cell cycle  Some affect any phase of the cell cycle   FYI: Three stages of therapeutic strategy: Induction – of complete remission (N. bone marrow cellularity = < 5% blasts!)  Consolidation - low dose chemo. to prevent recurrence.  Maintenance - of remission.  Treatment 2. Radiotherapy (“radiation”)   Produces unstable ions that damage cancer cells’ DNA. Used for localized malignancies. 3. Supportive Therapy    Used to support cancer patients Allow for more efficient and effective delivery of chemotherapy regimens by preventing delays or dose reductions due to low blood counts Examples are colony stimulating factors & EPO Treatment 4. Targeted Therapy  Monoclonal antibodies which bind directly to affected cell, activates compliment, and cell lysis. 5. Bone marrow or Stem Cell Transplantation (BMT, SCT)    Pt. should be in good clinical condition & in 1st clinical remission for best results. Minority donors desperately needed for the National Marrow Donor Program! The effort to isolate stem cells from non-embryonic sources is making tremendous strides. Treatment 5. Bone marrow or Stem Cell Transplantation (BMT, SCT)   Classic approach typically requires intensive chemotherapy, then total body irradiation. Three types of donors:  https://video.sea rch.yahoo.com/y hs/search?fr=yhs -trp001&ei=UTF8&hsimp=yhs001&hspart=trp &p=types+of+b one+marrow+tra nsplant&type=Y1 49_F163_202167 _090321#action =view&id=1&vid =b20b48c5621c 124220aaeeae5d 4431f1 Syngeneic – identical twin donor   Allogeneic – donor genetically different from recipient   Most rare and the most desired Most serious transplant complication is GVHD (? ____________________), Graft vs. Host Disease in which donor’s bone marrow Tcells destroy bone marrow & tissues of recipient. Autologous – patient’s own marrow or peripheral blood stem cells   Marrow is harvested, conditioned, and transplanted back in the patient Requires the presence of normal stem cells and reduction of malignant cells Common Clinical Symptoms of All Leukemias (to a greater or lesser degree) Due to bone marrow overcrowding: ? ____________ anemia. myelophthisic Due to anemia: malaise, fatigue, pallor (dyspnea if severe). Due to thrombocytopenia: Petechiae (pinpoint bruising) Epistaxis – nosebleed Hemorrhage (2nd main cause of death in leukemias!) Common Clinical Symptoms of All Leukemias (to a greater or lesser degree)  Due to extreme anemia: extramedullary hematopoiesis causing ____________________________, hepatosplenomegaly. NOTE: Hepatosplenomegaly may actually exacerbate anemia by inadvertently trapping RBCs (sequestration.)  Due to neutropenia:  Increased incidence overwhelming infections; this is primary cause of death in leukemia! Leukemoid reaction. vs. Leukoerythroblastic reaction 1. Leukemoid reaction:    Transient, reactive leukocytosis due to infection Temporary resemblance of peripheral blood picture to “leukemic picture” Severe left shift & very rare nRBCs. (WBCT > 50,000/uL!) Leukemoid reaction. vs. Leukoerythroblastic reaction 2. Leukoerythroblastic reaction (aka. Leukoerythroblastic anemia, or Leukoerythroblastosis): Presence of both nRBCs & left shift in peripheral blood Caused by bone marrow damage from a malignant, “space-occupying lesion”, with consequent extensive extramedullary hematopoiesis. May be mild or severe, & occurs in CML & in lymphomas. Leukemoid rxn. vs. Leukoerythroblastic rxn. So how could you tell these apart? 1.  Historically, a Leukocyte Alkaline Phosphatase (LAP) stain score: So what is LAP? An enzyme found in the secondary granules of neutrophils   The substrate naphthol AS-B1 phosphate is hydrolyzed by the enzyme at an alkaline pH, and dyed to produce a colored precipitate Two slides are obtained per patient, and activity is graded from 0 to 4+ (performed by two techs, and must agree within 10%) LAP reactivity LAP Stain LAP ↓ in early leukemia (Ex., early CML) because leukemic neutrophils are too abnormal to express the LAP that N., mature bands & segs would. Also, you see real leukoerythroblastosis (Lots of nRBCs!!) LAP ↑ in leukemoid reaction due to left shift, because there are tons of bands & segs full of secondary granules containing LAP, just waiting to attack the infectious invaders – it only looks like a leukemia because of the high WBC count. Also, you see only very rare nRBCs!!  Normal LAP scores range from 15 - 170 Leukemoid rxn. vs. Leukoerythroblastic rxn. 2. Now, with the acceptance of the WHO classification, LAP score is no longer used. Instead, the presence of the BCR/ABL1 gene, or t(9;22), identifies CML.