Exam 3 Flashcards
Leukemia
A malignancy of hematopoietic cells, where the chief manifestation is involvement of the blood and marrow.
Lymphoma
A malignancy of hematopoietic cells, derived from lymphocytes or their precursors, which presents primarily as a solid mass
Extramedullary myeloid tumor (aka granulocytic sarcoma)
A malignancy of hematopoietic cells, derived from myeloid cells or their precursors (granulocytes, monocytes, etc.), which presents primarily as a solid mass.
grade of a tumor
refers to the clinical aggressiveness of a malignancy, often related to its rate of growth, with higher grades being more aggressive / more rapidly growing.
What is the most common Chromosomal abnormalities found in hematologic malignancies?
chromosomal translocations
why are conserved chromosomal abnormalities important?
a) their persistent presence allows them to be used as diagnostic markers for certain hematologic malignancies b) their persistent presence suggests they place a critical role in the development of the hematologic malignancy they are associated with
What is thought to be the reason for frequent chromosomal translocations in lymphomas?
thought to be due to the natural susceptibility of the genome to translocations during normal periods of genomic instability, namely during the initial immunoglobulin / T-cell receptor rearrangement during the maturation of B cells / T cells, and during the class recombination and somatic hypermutation process during the activation of B cells.
what three viruses are known to play a role in the genesis of some lymphomas?
1) Epstein-Barr virus (EBV): Some cases of classical Hodgkin lymphoma, some cases of Burkitt lymphoma, some other B cell non-Hodgkin lymphomas 2) Human T cell leukemia virus-1 (HTLV-1): Causative factor in adult T cell leukemia/lymphoma (ATLL) 3) Kaposi sarcoma herpesvirus/Human herpesvirus-8 (KSV/HHV-8): Primary effusion lymphoma
what is the most common type of childhood cancer?
Leukemia is the most common type (37% of all childhood cancers) Lymphoma is the 3rd most common type of cancer representing 24% of childhood cancers
Myeloid malignancies
those arising from mature or immature members of the granulocytic, monocytic, erythroid, megakaryocytic, and mast cell lineages.
Lymphoid malignancies
those arising from mature or immature members of the B cell, T cell, and NK cells lineages.
what is included in multi parameter classification?
The WHO classification system draws from various different sources of information to diagnostically define entities. This information can include: - microscopic appearance of the malignant cells - histologic growth pattern of the malignant cells in the marrow, lymph node, or other tissue - presence or absence of specific cytogenetic findings or molecular findings - relative amount of malignant cells present in the blood or marrow - presence or absence of certain cell surface markers / cytoplasmic markers / nuclear markers
ACUTE LEUKEMIAS
Acute leukemias are usually due to the rapid accumulation of (usually) immature cells in the marrow. These immature cells often replace many of the normal marrow cells, resulting in cytopenias (thrombocytopenia, anemia, neutropenia, etc.) Often, but not always, the immature cell is the generic-appearing blast.
MYELODYSPLASTIC SYNDROME (MDS)
MDS is a group of conditions where a clonal population derived from a neoplastic hematopoietic stem cell takes over the marrow, and is not capable of making normal blood cells in one or more lineages (dysplasia). This disease is categorized in most cases by falling peripheral blood cell counts. Although many people regard MDS as a precursor to acute myeloid leukemia (AML), due to the high rate of progression from MDS to AML, MDS is arguably a malignancy in its own right, as many people die of MDS without progressing to acute leukemia, due to the failure of the marrow to make normal blood cells.
MYELOPROLIFERATIVE NEOPLASMS (MPNs)
MPNs are neoplastic clonal proliferations of the marrow where the clone makes normal functioning blood cells, usually in multiple lineages, but makes too many of them in one or more lineages. MPNs are classified into different types based on the underlying cytogenetic abnormality, the types of blood cell(s) being overproduced, and other data. MPNs also have a tendency to progress to acute leukemia, though this tendency in much less than for MDS.
CLASSICAL HODGKIN LYMPHOMA (CHL)
CHL is a very distinct clinical entity, driven by the infamous Hodgkin-Reed-Sternberg (HRS) cells. For a long time, the derivation of the HRS cell was not well understood; thus, CHL was classified as its own entity. Today we know HRS cells derive from B cells, but the disease still remains its own unique clinical entity, due to its unique natural course and unique treatment regimens.
NON-HODGKIN LYMPHOMA
The term non-Hodgkin lymphoma refers to any malignancy derived from mature B cells (excluding CHL or plasma cell neoplasms), T cells, or NK cells. The large majority are derived from B cells.
PLASMA CELL NEOPLASMS
This category is self-explanatory, and includes MGUS, plasmacytoma, and multiple myeloma.
two major categories of acute leukemia?
acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL).
at what level of differentiation do the genetic perturbations that cause AML occur?
at the level of the pluripotential stem cell or the level of one of the committed progenitors
at what level of differentiation do the genetic perturbations that cause ALL occur?
at the level of the lymphoid stem cell
Risk factors for acute leukemia:
A. Previous chemotherapy, especially DNA alkylating agents and topoisomerase-II inhibitors B. Tobacco smoke C. Ionizing radiation D. Benzene exposure E. Genetic syndromes including Down syndrome, Bloom syndrome, Fanconi anemia, and ataxia-telangiectasia.
Signs and symptoms of acute leukemia:
The signs and symptoms of acute leukemia are related to decreased numbers of normal peripheral blood cells due to marrow infiltration by leukemic cells. Symptoms - fatigue, malaise, dyspnea - easy bruisability, weight loss - bone pain or abdominal pain (less common) - neurologic symptoms (rare) Signs - anemia and pallor - thrombocytopenia, hemorrhage, ecchymoses, petechiae, funded hemorrhage - fever and infection (pneumonia, sepsis, perirectal access) - adenopathy, hepatosplenomegaly, mediastinal mass - gum or skin infiltration (rare) renal enlargement and insufficiency (rare) - cranial neuropathy (rare) Rarely, in acute leukemia patients who present with very high white blood cell counts, the leukemic cells themselves may cause hyperviscosity or thrombotic problems. In these instances, a pheresis machine may be used to selectively remove white blood cells from the blood (leukopheresis)
two subdivisions of acute lymphoblastic leukemia?
B-lymphoblastic ALL (B-ALL) and T-lymphoblastic ALL (T-ALL)
ALL - incidence
ALL has an incidence of between 1 and 5 cases per 100,000 persons per year (about 3,000 news cases per year in U.S.) 75% of cases of ALL occur in children under 6 years old
ALL - diagnosis
- Peripheral white blood cell count (WBC) may be markedly increased, normal, or decreased. - Lymphoblasts often express CD34, a marker of immaturity also often expressed by myeloblasts. - Lymphoblasts express TdT, a nuclear enzyme that is specific to lymphoblasts (i.e. not usually expressed by myeloblasts). TdT is also not expressed by mature lymphocytes.
B-lymphoblastic ALL (B-ALL)
B-ALL accounts for the majority (80-85%) of cases of ALL. B-lymphoblasts express B-lineage antigens (e.g. CD19, CD22, and/or CD79a). B-lymphoblasts usually do not express markers of mature B cells, such CD20 or surface immunoglobulin.
Cytogenetics of B-ALL
B-ALL with t(9;22)(q34;q11.2); BCR-ABL1: 25% of cases of adult B-ALL (but only 2% of childhood B-ALL) contain a t(9;22) resulting in the Philadelphia chromosome, similar to what is seen in chronic myelogenous leukemia (CML). In these cases of Ph+ B-ALL, the BCR-ABL fusion protein differs from that typically seen in CML, in that it is only 190kd (p190) (instead of the 210 kd fusion protein seen in CML). This is due to the use of a different breakpoint in the BCR gene in ALL than in CML. In both adults and children, Ph+ ALL has the worst prognosis of any subtype of ALL.
B-ALL with translocations of 11q23; MLL:
B-ALL with abnormalities of MLL is frequently seen in B-ALL in neonates and young infants. These have a poor prognosis, and the frequency of this finding is the reason for the generally poor outcome of neonatal ALL.
B-ALL with t(12;21)(p13;q22); ETV6-RUNX1
This finding is seen in 25% of cases of childhood B-ALL. Like AMLs with translocations of RUNX1 (see below), these cases of ALL have a very favorable prognosis.
T-lymphoblastic ALL (T-ALL)
T-ALL accounts for a minority of ALL cases (25-30%) In contrast to B-ALL, T-ALL more frequently occurs in adolescents and young adults than in children. In contrast to B-ALL, T-ALL more frequently present with a component of lymphoblastic lymphoma (T-LBL), often manifesting as a large mediastinal mass. If the disease does have leukemic (T-ALL) component, the disease is more likely to present with a high white blood cell count than B-ALL. T-ALL / T-LBL favors males over females. T-lymphoblasts express T-lineage antigens CD2, CD3, and/or CD7. They may express both CD4 and CD8 concurrently, or may express just one or neither of these. They often express T-lineage antigens only seen in immature T cells, such as CD99 and CD1a.
ALL - THERAPY AND PROGNOSIS
ALL is generally a good prognosis disease in children. In children, the complete remission rate following chemotherapy is greater than 95%, with cure rates of around 80%. In adults, ALL is a worse disease, with complete remission rates of 60-80%, and cure rates of less than 50%.
PROGNOSTIC FACTORS FOR ALL:
- Age: worse prognosis for infants (10 years) or adults - White blood cell count: worse prognosis if markedly elevated white blood cell count at time of diagnosis. - Slow response to therapy / small amounts of residual disease after therapy: worse prognosis if either of these occurs - Number of chromosomes: very favorable prognosis for hyperdiploidy (>50 but
AML - INCIDENCE
Worldwide incidence of around 3 cases per 100, 000 persons per year Average age at diagnosis: 65 years old Rare in children and young adults (AML only accounts for around 10% of childhood leukemia)
AML - DIAGNOSIS
The diagnosis of AML is usually based on the identifications of increased myeloblasts accounting for 20% or more of nucleated cells in the marrow or peripheral blood. This diagnosis can be made by microscopic review of bone marrow aspirate smears or peripheral blood smears, or by flow cytometric review of marrow aspirate material or peripheral blood, or by microscopic (and possibly immunohistochemical) review of the marrow core biopsy. There are other, rarer ways, not worthy for discussion here, by which the diagnosis of AML can be established. An exception to the requirement for 20% myeloblasts for the diagnosis of AML occurs if one can document the presence of certain recurrent cytogenetic findings. These will be mentioned below.
AUER ROD
Auer rods are fused azurophilic granules forming small stick-like structures in the cytoplasm. The presence of Auer rods allows the identification of a blast as a myeloblast. Furthermore, they are only seen in abnormal myeloblasts
CD34
a generic marker of immaturity commonly seen on myeloblasts, but can also be seen in lymphoblasts.
cytogenetic analysis
(karyotyping - less sensitive; and FISH - more sensitive)
molecular analysis
(RT-PCR of mRNA transcript of fused genes - very sensitive)
AML - PROGNOSIS
Mean survival times for AML patients range from less than 1 year for patients with adverse risk cytogenetics, to more than 10 years in patients with favorable risk cytogenetics. Approximately 60% of AML cases will reach complete remission after chemotherapy. Rate of relapse varies according to prognostic factors. For many patients with AML with poor prognostic factors, or for many patients with relapsed AML, autologous stem cell transplant (SCT) is the preferred treatment. Due to the high morbidity of the transplant process, consideration of SCT must take into account the patient’s performance status (i.e. a measure of the patient’s overall health/robustness).
Contrast acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) in regards to demographics of affected patients, and prognosis.
AML is a much more heterogeneous disease than ALL (many more types) AML is typically a disease of adults: - average age at diagnosis of AML: 65 - only ~10% of childhood leukemias are AML AML incidence is around 3 cases per 100K persons per year (similar to ALL)
List risk factors for acute leukemia, while recalling that the majority of acute leukemias occur in the apparent absence of risk factors.
Previous chemotherapy, especially DNA alkylating agents and topoisomerase-II inhibitors Previous exposure of active marrow to ionizing radiation Tobacco smoke Benzene exposure Genetic syndromes, including Down syndrome, Bloom syndrome, Fanconi anemia, and ataxia-telangiectasia
List common signs and symptoms exhibited by patients with acute leukemia at initial presentation, and explain the reasons for these findings.
Presenting signs/symptoms usually result from replacement of the normal marrow cells by leukemic cells. They might include: Signs/symptoms of anemia: fatigue, malaise, pallor, dyspnea Signs/symptoms of thrombocytopenia: bruising, petechiae, hemorrhage Signs/sympyoms of neutropenia: fever, infections More rarely, presenting signs/symptoms may be directly attributable to effects of the leukemic cells. These include: Thrombotic events due to increased blood viscosity (known as leukostasis; seen in the setting of leukemia with very high WBC count) Disseminated intravascular coagulation (DIC), which can be initiated by the leukemic cells in some types of AML Direct infiltration of skin, gums, lymph nodes, and/or other tissues by leukemic cells