Hematology 425 Leukocyte Neoplasms

1. Hematology 425 Leukocyte Neoplasms Russ Morrison November 29, 2006

2. Leukocyte Neoplasms • Neoplasm is defined as an abnormal tissue that grows by cellular proliferation more rapidly than normal and continues to grow after the stimuli that initiated the new growth ceases • A neoplasm may be benign as with a tumor or malignant in cancer(s) • A leukocyte neoplasm is abnormal cellular proliferation in the WBC series

3. Leukocyte Neoplasms • Leukemias are a group of diseases manifested by malignant, unregulated proliferation of cells normally found in the bone marrow • Leukemia may involve any of the blood-forming cells or their precursors • Leukemia may be found in metastatic lesions throughout the body, in the brain, liver, spleen and lymph nodes

4. Leukocyte Neoplasms • Though leukemias progress differently, the unregulated proliferating cells have four things in common • They usually replace normal marrow • They eventually interfere with normal marrow function • They may invade other organs • The eventually cause death if they go untreated

5. Leukocyte Neoplasms • Leukemias are relatively new diseases since they were first described in 1845 • In 1900, it was reported that acute and chronic leukemias involve different types of WBCs • In chronic leukemias, mature cells are predominant while in acute leukemias, immature cells (blasts) hold center stage

6. Leukocyte Neoplasms • Since the 1900s, leukemias have been studied with the microscope, cytochemical stains, electron microscopy, immunologic nuclear and surface markers and cytogenetic techniques • Standardized subclassification of leukemia subtypes leads to better treatments through pharmaceutical research • Today, we are at a threshold of development of targeted therapies, better treatments and cures for both the acute and chronic leukemias

7. Clinical Classification of Leukemia • Leukemias are divided into acute and chronic diseases based on their presenting signs and symptoms as well as the cell type involved • Acute leukemias are characterized by abrupt onset of clinical signs (infection, hemorrhage and pallor) and symptoms (fatigue, weakness, bone and joint pain) • Death occurs within months in acute leukemia if treatment is not begun

8. Clinical Classification of Leukemia • WHO classification of acute leukemias requires a minimum of 20% blast forms (myeloid or lymphoid) in either the PB or BM • PB WBC counts may be increased, decreased or normal, though typically they are increased • Normocytic anemia and neutropenia are classic states, while thrombocytopenia is usually present

9. Clinical Classification of Leukemia • Chronic leukemias have an insidious onset of signs (pallor, splenomegaly and/or hepatomegaly, weight loss) and symptoms (weakness, fatigue, depression) • They usually occur in adults and death occurs years after diagnosis • WBC counts are variable, though usually higher than seen in acute leukemia and cell forms are more mature • Platelet counts are normal or increased • Acute vs Chronic is compared in Table 32-1

10. Classification by Cell Type • A PB smear can initiate a diagnosis of acute or chronic leukemia • Additional information is gathered to subcategorize the lymphocytes in CLL and some of the CMLs using cytochemistry, flow cytometry, PCR and cytogenetics • Genetic testing to determine specific gene abnormalities will become standard within the next few years

11. Lymphoblast 2-3 times the size of a normal lymphocyte Have scant blue cytoplasm Uniform coarse chromatin Inconspicuous nucleoli Myeloblast 3-5 times the size of a normal lymphocyte Moderate grey cytoplasm Uniform fine chromatin 2 or more prominent nucleoli Auer rods Morphologic identification of Lymphoblasts vs myeloblasts

12. ALL

13. AML (note Auer Rod)

14. Morphologic Subtypes of ALL • Three morphologic subtypes of “blasts” have been described according to the FAB classification system • Little, if any, prognostic information is gained from this classification • Subtypes are termed L1, L2 and L3 based on the following descriptions

15. ALL – L1 Lymphoblasts • Small • Scant blue cytoplasm • Round nuclei • Indistinct nucleoli • The most common type of ALL

16. ALL – L1 Lymphoblasts

17. ALL – L2 Lymphoblasts • 2-3 times the size of a normal lymphocyte • Moderate cytoplasm • Irregular nuclear membrane • Prominent nucleoli • May resemble AML

18. ALL – L2 Lymphoblasts

19. ALL – L3 Lymphoblasts • Large • Midnight blue cytoplasm • Cytoplasmic vacuoles are present • 3-5 nucleoli

20. ALL – L3 Lymphoblasts

21. Other Classifications of Acute Leukemias - Cytochemical • Cytochemical staining classification systems were developed by FAB • The current panel of stains includes myeloperoxidase, Sudan black B, chloroacetate esterase, and nonspecific esterase • Table 32-2 shows the FAB classification of acute leukemias by cytochemical reactions

22. Other Classifications of Acute Leukemias - immunologic • Monoclonal antibodies and flow cytometry added to morphology and cytochemical stains brings the accuracy of identification of leukemic cell lines to 95% • The technique is more commonly used for lymphoid rather than myelogenous cell lines • A panel of cell line markers is used because no single surface marker is specific • Table 32-3 shows the immunologic classification of these cells

23. Other Classifications of Acute Leukemias - Cytogenetic • Chromosomal alterations aree associated with leukemic cells • Cytogenetic studies can be used to detect clonal abnormalities • Clonal abnormalities can be of number (ploidy) or of structure (translocations, deletions and rearrangements)

24. Other Classifications of Acute Leukemias - Molecular • Molecular Diagnostics/PCR are able to identify genetic mutations in both acute and chronic leukemias • As these methods develop, the diagnosis and classification of acute and chronic leukemias will be performed by molecular methods

25. Acute Leukemias - ALL • Acute lymphoblastic leukemia (ALL) is a disease of childhood • Most cases occur between the ages of 2 and 10 years of age • All is rare in adults, but a second cluster of incidence occurs among elderly patients • Treatment of childhood ALL now yields a 90% rate of complete remission with a 60% cure rate

26. Acute Leukemias - ALL • Adults with ALL do not fare as well having a 68-91% remission rate and a 25-41% cure rate • Approximately half of patients with ALL have increased WBC counts and they may or may not have lymphoblasts in the PB • Neutropenia, thrombocytopenia and anemia are usually present • This pancytopenia causes fatigue, fever and bleeding and there is often lymph node enlargement

27. Acute Leukemias - ALL • Hepatomegaly and splenomegaly are often present as well as bone pain due to infiltration of leukemic cells into the periosteum • Eventually, the meninges are invaded by malignant cells and lymphoblasts are found in the CSF • Lymphoblast infiltration into the testes and ovaries is common, especially in relapse

28. ALL - Prognosis • Prognosis is dependent on the age of the patient at the time of diatnosis • It is also related to the lymphoblast load and immunophenotype • Chromosomal translocations (ex Philadelphia Chromosome 5(9;22)) are proving to be a strong predictor of adverse treatment outcomes for both children and adults

29. ALL - Prognosis • Patients 2-10 years of age have the best prognosis • Children less than 1 year of age do poorly • Children between 1 and 2 have an intermediate success rate, as do teenagers and young adults • Lymphoblast count > 20-30 x109/L, hepatosplenomegaly and lymphadenopathy all decrease the effectiveness of treatment and the patients are considered “high risk”

30. ALL - Prognosis • Other variables showing decreased outcomes include race (native American), karyotypic abnormalities and sex (male) • Morphology – • The three major FAB classifications FAB-L1, FAB-L2, and FAB-L3 were discussed in Chapter 32

31. ALL - Immunophenotyping • Morphology is the first tool in distinguishing ALL from AML, but immunophenotyping is the best indicator of a cell’s origin • Immunologic classification of ALL should be performed in all cases due to the prognostic implications

32. ALL - Treatment • Success with treatment is divided by age of presentation • Intrathecal methotrexate is used with children • Methotrexate is a folate antagonist and kids on this drug will be megaloblastoid • Adults are treated with daunorubicin, vincristine and prednisone (all with side effects) • Stem cell or bone marrow transplantation is the last line of treatment for unresponsive or relapsed ALL

33. Acute Myeloid Leukemia - AML • AML is the most common leukemia in children less than 1 year of age • AML is rare in older children and adolescents • A second age focus of AML occurs among adults 40 years of age • AML is rapidly fatal if not treated • 8 types of AML (M0 thru M7) have been described

34. AML – Clinical Presentation • Clinical presentation is nonspecific reflecting the decreased production of normal BM elements • WBC count is usually between 5000 and 30,000/mm3, but may be as high as 200,000 or as low as 1000 • Myeloblasts are present in the PB of 90% of patients • Anemia, thrombocytopenia and neutropenia lead to symptoms of pallor, fatigue, bruising, bleeding and fever with infections

35. AML – Clinical Presentation • DIC and other bleeding abnormalities occur, especially with M3-promyelocytic and monocytic-M5 forms of AML • Infiltration of malignant cells into the gums and mucous membranes, as well as the skin are is seen in M4-myelomonocytic and M5-monocytic types • Bone and joint pain is the first symptom in 25% of patients • Splenomegaly is seen in half of AML patients, but lymph node enlargement is rare

36. AML – Clinical Presentation • AML patients do not usually exhibit symptoms when the CNS is infiltrated with blasts • Elevated uric acid, potassium and phosphate levels along with decreased calcium (termed tumor-lysis syndrome), renal failure, tetany and lethal heart arrythmias may develop

37. AML – Subtypes • Micrographs of the AML subtypes are exhibited in the text and atlas • The FAB cooperative group has defined 8 subtypes (M0-M8) of AML based on bone marrow morphology and cytochemical reactions • In the FAB classification, 2 types of myeloblasts have been described • Type 1 have typical blast morphology and no azurophilic granules • Type 2 may contain a small number of primary granules

38. AML – Subtype M0 • Acute myeloblastic leukemia, minimally differentiated • Blasts do not display morphologic myeloid characteristics • Fewer than 3% of blasts exhibit myeloperoxidase or Sudan black B positivity • Auer rods are not sen • May express antigen TdT

39. AML – Subtype M1 • Acute myeloblastic leukemia, without maturation • Displays minimal myeloid differentiation • Myeloblasts constitute more than 30% of the BM nucleated cells • M:E ratio is greater than 1 • 90% of the erythroid cells are myeloblasts • 3% of the myeloblasts show positivity when stained with myeloperoxidse of Sudan black B • Easily confused with ALL (L2 type) • Accounts for 20% of cases of AML

40. AML – Subtype M2 • Acute myeloblastic leukemia, with maturation • 30% of nucleated cells must be blasts in the BM film and myeloid cells outnumber NRBCs • Blasts constitute fewer than 90% of nonerythroid cells and there is maturation beyond the promelycyte in more than 10% of nonerythroid cells • Majority of blasts stin positively when stained with myeloperoxidase or Sudan black B • Subtype accounts for 30% of cases of AML

41. AML • Induction therapy in M1 and M2 leukemia is usually effective, resulting in sufficient return of normal marrow responses for an autologous bone marrow transplant • Drugs frequently used are daunorubicin and cytosine arabinoside • Cardiac monitoring is necessary due to side effects • Cytosine arabinoside is active against the nucleus, resulting in a megaloblastoid presentation of the CBC

42. AML – Subtype M3 • Acute promyelocytic leukemia • May be one of two types, hypergranular or microgranular • Stain strongly positive with myeloperoxidase • M3 patients must be recognized because bleeding problems (DIC) occur when these patients are treated and the granules are released • Make up approximately 15% of all AML cases • Treatment with all-trans retinoic acid (ATRA) a form of Vitamin A causes the cells to undergo maturation (cells have a defective vitamin A receptor)

43. AML – Subtype M4 • Acute myelomonocytic leukemia • Has malignant cells with both granulocytic and monocytic features • BM more than 30% of nucleated cells are blasts • When the M:E ratio is greater than 1, more than 20% of nonerythroid cells are monocytic • A small percent has moderate eosinophilia (AML-M4Eo), have CSF involvement and a better remission rate and response to chemotherapy

44. AML – Subtype M5 • Acute monocytic leukemia • Accounts for 12% of AML • Diagnosis based solely on the BM morphology • More than 30% of cells are blasts • More than 80% of cells are monocytic, less than 20% granulocytic • Two subtypes recognized, M5a and M5b • Skin involvemen and gum infiltration may be seen in both types

45. AML – M5 – Gum infiltration

46. AML – Subtype M6 • Acute erythroleukemia • Rare, 3% of AML cases • The only AML with hyperplasia of erythroid precursors

47. AML – Subtype M7 • Acute megakaryocytic leukemia • The rarest type of AML at <1% of cases • In adults, many cases are preceded by a myeloproliferative disorder with pancytopenia or myelofibrosis • In children it is more frequent among patients under three years of age with Down syndrome • Response to therapy is poor

48. Other Acute Myeloid-like Leukemias • Acute undifferentiated leukemia and hybrid leukemias are often treated as AML, but are not necessarily related • Undifferentiated acute leukemia is a rare disorder in which the lineage of the blasts can not be determined • Hybrid leukemias are leukemias with both lymphoid and myeloid characteristics

49. Chronic leukemias – lymphocytic disorders • There are two major types of chronic lymphoid leukemias • Chronic lymphocytic leukemia (CLL) • Hairy cell leukemia There are also a few other forms of chronic lymphoid leukemias that are rare and not discussed in this series

50. Chronic Lymphocytic Leukemia • CLL is the most common type of leukemia • Usually occurs in older patients • Most commonly found in patients older than 40 (though youngest case was 22) • Affects twice as many men as women • No specific chromosomal abnormality has been associated with CLL