Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
Hematology (1)
Disorders of the hematopoietic stem cell
 Myeloaplastic disorders - a deficiency of the production of the cells of
the marrow but the cells that are produced are normal;
 Myelodysplastic disorders - ineffective production of cells that are
abnormal in morphology and biochemistry;
 Myeloproliferative disorders - overproduction of one or more of the
cell lineages. The cells may also have dysplastic characteristics.
The boundaries among these categories are not always distinct.
The myeloaplastic disorders
Diminished production of cells in the marrow results in peripheral
cytopenia. When the stem cell is affected, the proliferation of all cell
lineages is diminished -> pancytopenia ("aplastic anemia"). In other
cases, only a single line may be afflicted (e.g., amegakaryocytic
thrombocytopenia).
Congenital myeloaplastic disorders
Congenital defect in the stem cell -> aplastic anemia (Fanconi's
syndrome).
Acquired aplastic anemia
Pancytopenia of variable degree can occur secondary to chemotherapeutic
agents or to irradiation, or as an idiopathic acquired condition.
The cytotoxic drugs designed to treat malignancy usually interrupt the
cell cycle or alter intracellular processes so that cell death supervenes.
Stem cell function can also be markedly reduced by viruses.
Idiopathic acquired aplastic anemia is thought to be due primarily to
autoimmune suppression of the stem cells.
Clin: aplastic anemia is a disease of young adults, with peak incidence at
age 20 to 25, and of the elderly ~ 60 to 65. Men and women are equally
affected.
Usually all three cell lines in the peripheral blood are deficient in number
but normal in morphology. The reticulocyte count is reduced; the marrow
is hypoplastic and may contain primarily lymphocytes.
Therapy
 supportive - transfusions of red blood cells or platelets as needed and
the appropriate use of antibiotics. Transfusions should be limited in
patients who are candidates for bone marrow transplantation, as they
may induce alloimmunization. The most definitive treatment of severe
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
aplastic anemia is bone marrow transplantation; it is age-limited (< 50
years) and the overall success rate in aplastic anemia is 70%.
 When bone marrow transplantation is not an option,
immunosuppression using antithymocyte or antilymphocyte globulin
and cyclosporine (a T cell suppressing agent) is about equally
successful. The overall survival is ~ 60%.
The myelodysplastic disorders
All three lines are usually affected. All may result in acute myeloblastic
leukemia.
Myelodysplastic syndromes (MDSs). A slow and insidious development
of bone marrow failure characterized by anemia and thrombocytopenia or
a combination of both. MDSs especially appear to occur after treatment
for Hodgkin's disease or ovarian carcinoma but may occur after any
chemotherapy with alkylating agents. The anemia in MDSs is typically
macrocytic. The bone marrow is typically hypercellular with increased
iron stores and morphologically abnormal erythroid precursors.
Hypocellular bone marrow in MDSs imparts a poor prognosis. Increased
immature myeloid forms (blasts) may herald progression to acute
leukemia.
Treatment of MDSs
is primarily directed toward improving the cytopenias. Transfusions of
red blood cells and platelets. Some patients with refractory anemia with
ringed sideroblasts respond to large doses of pyridoxine. Growth factors,
esp. recombinant human erythropoietin may improve the anemia in some
patients. Bone marrow transplantation in younger patients should be
considered.
Paroxysmal nocturnal hemoglobinuria
is an acquired stem cell disorder characterized by intravascular
hemolysis, unusual venous thromboses, and evidence of diminished
hematopoiesis.
It is the result of the somatic mutation of a gene on the X chromosome of
a stem cell.
Clin: hemoglobinuria results from the intravascular hemolysis of the
abnormal cells. The hemoglobinuria is nocturnal because complement is
activated at night and is paroxysmal because complement is activated by
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
infections, physical stress etc. It results in a marked loss of iron in the
urine. It can result in acute renal failure and in chronic renal damage.
Venous thromboses occur in ~ 40% of patients.
Lab: intravascular hemolysis + neutropenia and/or thrombocytopenia.
Ham acidified serum lysis test: hemolysis of the abnormal red cells by the
activation of complement.
Th: bone marrow transplantation. Glucocorticoids may diminish the
activation of complement in moderately high doses (15 to 30 mg/day in
adults). Anabolic steroids may also improve the anemia. All patients
(except those receiving transfusions) should take iron and folic acid
supplements.
Mean survival is 8 to 12 years.
Myelofibrosis
is characterized by abnormal hematopoiesis and replacement of the bone
marrow by fibrous tissue.
Disruption of the structure of the marrow -> circulation of immature
cells. Extramedullary hematopoiesis. The primary problem may be
dysplasia of the megakaryocytes, which results in the local elaboration of
cytokines that promote the growth of fibrous tissue.
Clin: myelofibrosis is a chronic disease of the middle aged and elderly.
Anemia, hepatosplenomegaly, with time other cytopenias. The bone
marrow cannot be aspirated, but the biopsy shows strands of fibrous
tissue with nests of hematopoietic cells. Megakaryocytes are plentiful and
are often bizzare in morphology, with hyposegmentation of the nucleus.
Th: the most definite treatment is bone marrow transplantation. Mild
chemotherapy, such as 6-mercaptopurine 100 mg/day may be used in the
proliferative phase. Splenectomy may be necessary. The mean survival
from diagnosis is 5 to 10 years.
Myeliproliferative disorders
The cells are normally differentiated (except for the acute leukemias) but
appear to have escaped the usual controls on growth. The ultimate result
may be acute myeloblastic leukemia.
Polycythemia rubra vera
A clone of stem cells produces erythroid precursors autonomously. The
production of erythropoietin is suppressed.
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
Clin: older persons are affected. Plethora of the face, splenomegaly in >
60% of patients. Patients may have erythromyalgia of the feet and may
have pruritus, esp. after a bath. The hematocrit is usually > 53%. The red
cells are normal in appearance but may be hypochromic if iron deficiency
is present. The white count is often elevated above 12,000/mm 3, and the
platelet count is above 450,000/mm3. Arterial hypoxia is not present. The
plasma erythropoietin level is usually undetectable. The leukocyte
alkaline phosphatase is often elevated in the absence of infection.
Course of the disorder and treatment
Polycythemia vera is a chronic disorder that is complicated by
thromboses (frequently arterial) that terminates either in leukemia or
myelofibrosis.
Patients with nonaggressive and mild disease may be treated with
phlebotomy, whereas those with increased platelet counts or any tendency
to thrombosis should be treated with hydroxyurea. Alkylating agents
(chlorambucil) and P32 often lead to leukemia and other neoplasms.
Chronic myelogenous leukemia (CML)
Def: a malignant stem cell disorder classified as a myeloproliferative
disease. The Philadelphia (Ph1) chromosome is a translocation of the
long arm of chromosome 22 to chromosome 9. The product of this
translocation is a tyrosine kinase, which promotes granulocyte
proliferation.
CML usually occurs in adults but can occur at any age. CML is often
found incidentally when an elevated white blood cell count is found.
Thrombocytosis is often present. The spleen is usually enlarged.
Bone marrow examination reveals myeloid hyperplasia without a
significant increase in blast forms. Megakaryocytes may be increased.
Th: the antimetabolite hydroxyurea (a ribonucleotide reductase inhibitor)
is used as initial "debulking" treatment (formerly busulfan).
Alpha-interferon, alone or combined with cytosine arabinoside, may
decrease the number of Ph1-positive cells in the bone marrow and enrich
the normal clone of cells. Bone marrow transplantation represents the
only potentially curative means of treating CML.
Most patients with CML present in the "chronic" phase of the disease,
which usually last from 3 to 5 years. Adverse prognostic features include
advanced age, basophilia, severe thrombocytosis, or more than one
chromosome abnormality.
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
"Accelerated" phase - the white blood cell count and splenomegaly
become more difficult to control. Either thrombocytopenia or marked
thrombocytosis may herald the accelerated phase.
"Blast crisis" - a genuine acute leukemia, which is usually of myeloid
phenotype. The treatment of blast crisis is difficult and unsatisfactory.
Usually, blast crisis ends in death between 3 and 6 months after its
appearance.
Essential thrombocythemia
It is due to a clonal growth of stem cells that produce excess numbers of
megakaryocytes. The clinical manifestations are primarily those of
thrombosis in small or large vessels.
Dg: increased platelet count (> 600,000/mm3) in the absence of other
causes (infection, iron deficiency, nonhematologic malignancy) that
persists over at least 2 months. The platelets may appear abnormal.
Splenomegaly may be present. The bone marrow is usually cellular and
contains large number of megakaryocytes.
Th: plateletapheresis (in patients with cerebral symptoms). Hydroxyurea
is commonly used. Patients with essential thrombocythemia rarely
progress to leukemia but may have myelofibrosis as a late complication.
Acute leukemia
The acute leukemias are divided into two broad categories: acute
lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML).
ALL is primarily a disease of children and represents > 90% of the acute
leukemias in this age group. AML represents at least 80% of acute
leukemias in the age group over 20 years.
French - American - British (FAB) classification of acute leukemia
Acute myelocytic leukemia
M1
M2
acute myelocytic leukemia without differentiation
acute myelocytic leukemia with differentiation
M3
acute promyelocytic leukemia
M4
acute myelomonocytic leukemia
M5
acute monocytic leukemia
M6
M7
erythroleukemia
megakaryocytic leukemia
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
Acute lymphocytic leukemia
L1
predominantly "small cells" (twice the size of normal
lymphocyte), homogeneous population; childhood variant
L2
larger than L1, more heterogeneous population; adult variant
L3
"Burkitt-like" large cells, vacuolated abundant cytoplasm
Diagnosis is initially suspected by morphologic evaluation of the
peripheral blood and bone marrow aspiration and biopsy and may then be
confirmed by using histochemical stains and immunophenotyping of
surface and cytoplasmic markers. Chromosome studies are helpful.
Clin: anemia, thrombocytopenia -> fatigue, malaise, bleeding, and
infection.
Th: If the white count is > 100,000/µl, the patient is at high risk for
leukostasis (obstruction as small vessels by rigid blast cells). Therapeutic
leukopheresis and specific chemotherapy should be initiated immediately.
The goal of treatment is to destroy the leukemic cells and produce a
complete remission during which leukemia cells cannot be found in the
peripheral blood or bone marrow.
Initial therapy = induction. In AML: cytosine arabinoside, usually given
as a 7-day infusion along with a second drug, usually an anthracycline
such as daunorubicin, idarubicin, or mitoxantrone. Induction
chemotherapy for AML produces complete remission in ~ 75% of
patients under 60 years of age and in ~ 50% of patients over 60.
Chemotherapy given soon after the induction of complete remission is
termed "consolidation" chemotherapy and may employ the same drugs. In
AML, an exact schema is not universally agreed upon. Long-term
disease-free survival in younger patients with AML has been described in
up to 30% of patients treated by conventional means and in a similar
proportion of patients who go on to bone marrow transplantation.
Th of ALL: initial induction usually involves multiple agents, including
vincristine, prednisone, daunorubicin, cyclophosphamide, and Lasparaginase. In children, up to 90% of patients achieve complete
remission, and an increasing proportion of patients are alive and in
complete remission > 5 years after initial induction. The aggressive longterm maintenance chemotherapy lasts up to 2 or 3 years with early
prophylaxis of the CNS with intrathecal chemotherapy with or without
whole brain radiation.
Th of acute promyelocytic leukemia is unique. All trans retinoic acid
(ATRA, tretinoin) binds to the retinoic acid receptor, a part of the
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
t(15,17) translocation. In most patients, this stops the process of DIC and
may lead to maturation of the leukemic clone into "normal" granulocytes.
Disorders of Lymphocytes
Lymphocytes are derived from hematopoietic stem cells. From a
precursor are derived three cell lines: B cells, T cells, and natural killer
(NK) cells. These differentiation steps are directed by cytokines and
cellular interactions in a very complex pattern.
B cells
Steps proceeding from pre-B cells through B cells to plasma cells. The
cells at each step are identified by two characteristics:
 the immunoglobulin genes undergo rearrangements that will permit
the expression and secretion of immunoglobulins;
 cell surface markers appear that can be detected by monoclonal
antibodies.
The final step consists of differentiation into plasma cells, again under
external influence of T cells. Plasma cells lose most of the surface
markers. Antibody production is shown by an enlarged Golgi apparatus,
which displaces the nucleus, and by deep blue cytoplasm because of the
mRNA being generated.
T cells
Cells destined to be T cells acquire an antigen, CD7, which they maintain
throughout their development. These cells migrate from the bone marrow
to the cortex of the thymus, where they undergo a series of changes
orchestrated by the thymic cells and by various cytokines.
As cells migrate toward the medulla of the thymus, they acquire both the
CD4 and the CD8 surface markers and begin to synthesise the T cell
receptor. This receptor, crucial to many T cell functions, is composed of a
heterodimer. The components of these complexes belong to the
immunoglobulin superfamily. The cells acquire the CD3 complex as well
as the CD4 and CD8 molecules. As they proceed through the thymus,
most are destroyed by apoptosis or programmed cell death initiated by
self-antigens presented to T-cells by the epithelial cells of the thymus;
thus, clonal selection occurs that allows only the T cells bearing non-selfrecognizing receptors to survive.
As cells mature, they lose either the CD4 or the CD8 surface molecule.
CD4+ cells generally serve as helper cells in the immune system, whereas
CD8+ cells generally have suppressor functions.
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
NK cells
Some cells do not bear the defining surface molecules of B or T cells and
their immunoglobulin and TcR genes do not undergo rearrangement.
These cells are able to destroy cells without using immunoglobulin - like
molecules -> natural killer cells. They have large size with abundant
cytoplasm, which contains large azurophilic granules; they are sometimes
called large granular lymphocytes (LGL). They have the CD56 and CD16
antigens.
In lymph nodes, the follicles contain mainly polyclonal B cells; T cells
are found throughout the remainder of the lymph node. The distribution
of the lymphocytes in the spleen is much like that in the lymph node. In
the peripheral blood, the majority of lymphocytes are small, resting cells.
About 80 to 85% are T cells; 75 to 80% of these are CD4, and the
remainder, CD8 cells. The B cells represent 15% of circulating
lymphocytes and are also polyclonal.
Disorders of the Lymphatic System
Infectious disorders
Lymphocytes play a major role in response to any infection → an
increase in lymphocytes in the peripheral blood in viral diseases (mumps,
hepatitis, varicella, and infectious mononucleosis) or in certain bacterial
diseases (pertussis, brucellosis, and some forms of syphilis). This
response is always polyclonal.
Local or general enlargement of the lymph nodes in infection.
Neoplastic disorders
Chronic lymphocytic leukemia (CLL)
is the most common form of leukemia. > 90% occur in patients over 50
years of age. Men develop CLL twice as often as do women.
CLL is often found incidentally – leukocytosis composed primarily of
small lymphocytes.
Dg: > 15,000 lymphocytes/μl in peripheral blood and at least 40% of the
cells in the bone marrow being lymphocytes. Lymphadenopathy and/or
splenomegaly are common.
Poor immunologic competence → hypogammaglobulinemia and increase
in infection or the presence of autoimmune phenomena – Coombs
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
positive AIHA, immune thrombocytopenic purpura or immune
granulocytopenia. Pure red cell aplasia is unusual.
CLL represents a clonal proliferation, usually of B lymphocytes.
CLL from T lymphocytes has a poorer prognosis and skin involvement is
often seen.
Human T-cell leukemia virus (HTLV)-1 infection a more virulent form of
T-cell CLL. It may present with hypercalcemia, lytic bone lesions, and
severe debility; treatment is rarely effective.
The cause of CLL is not known, no genetic basis has been discovered.
Clinical staging for CLL
Level of risk stage
descriptions
low
0
lymphocytosis only in blood and bone marrow
intermediate
I
II
lymphocytosis plus enlarged lymph nodes
lymphocytosis plus enlarged liver and spleen
(+ enlarged nodes)
high
III
lymphocytosis plus anemia (not autoimmune)
(+ enlarged nodes, spleen or liver)
IV
lymphocytosis plus thrombocytopenia (not
autoimmune) (+ enlarged nodes, spleen or liver)
Th: patients in stages 0, I or II may be observed without treatment until
they develop bulky lymph node enlargement, disease symptoms such as
fevers, night sweats, malaise, or fatigue; or cytopenia
Initial treatment – usually a single alkylating agent (chlorambucil,
cyclophosphamide) with the addition of prednisone if symptoms are
present or if autoimmune phenomena occur.
In more advanced disease fludarabine → may produce complete
remission through apoptosis.
Radiation therapy may be used for bulky tumor mass, lymph node
enlargement, or large splenomegaly.
CLL may transform into a clinically more malignant neoplasm with
features of high-grade lymphoma (Richter’s syndrome).
Increased infections during the evolution of CLL should be treated with
antibiotics. Intravenous gammaglobulin is useful.
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
Hairy Cell Leukemia (leukemic reticuloendotheliosis)
~ 1 / 2% of all leukemias. It usually presents as a slowly developing
pancytopenia with splenomegaly.
Hairy cells look like lymphocytes with fine cytoplasmic projections.
Unlike typical B cells, they are capable of phagocytosis.
Splenectomy may be useful. Chemotherapy with standard alkylating
agents does not help. Most patients respond to alpha-interferon, 2’deoxycoformycin, or 2-chlorodeoxyadenosine. Granulocyte colonystimulating factor may correct leukopenia. The median survival is 3 – 5
years.
Lymphomas
The most common clinical presentation is asymptomatic enlarged lymph
node in the cervical, axillary or inguinal region.
Non-Hodgkin’s Lymphomas
monoclonal proliferation of a malignant cell of lymphoid origin, either a
T or a B cell. The Epstein-Barr virus has been implicated in African
Burkitt’s lymphoma and in lymphomas arising from immunosuppressive
therapy after organ transplantation; HIV in AIDS-related lymphomas.
Non-Hodgkin’s lymphomas are classified by pathologic subtype,
immunophenotype, and clinical stage.
Major lymphoma cell types:
- small, well differentiated lymphocytes
- small lymphocytes with cleaved nuclei (follicular center cells)
- large lymphoid cells
Non-Hodgkin’s lymphomas often present with advanced-stage disease
and may occur in extranodal sites (GIT, CNS, bone marrow)
True stage I or II are unusual; may be treated with local radiation
therapy. Patients with stage III and IV disease are usually treated with
chemotherapy.
In low-grade lymphoma, a single alkylating agent (chlorambucil,
cyclophosphamide) may control the disease. Corticosteroids are often
added. Vincristine and doxirubicine may be used.
Bone marrow transplantation and peripheral stem cells offer the
possibility of curing non-Hodgkin’s lymphomas.
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Seminars for the 5th year
summer term
Prof. MUDr. Jiří Horák
Hodgkin’s disease
Bimodal distribution - young adults and ~ 60 years
Usual presentation: asymptomatic lymph node enlargement
“B” symptoms: fever, night sweats, weight loss > 10%
Subtypes of Hodgkin’s disease
subtype
rel. frequency
description
prognosis
lymphocyte
5 – 15%
few RS cells
favorable
often in young;
responds to
mediastinal
radiation
often in elderly;
many RS cells
less sensitive to
radiation
abundant RS
less favorable
predominance
nodular sclerosis 40 – 75%
mixed cellularity 20 – 40%
lymphocyte
5 – 15%
depletion
cells
Dg: Reed-Sternberg cells
Staging criteria for Hodgkin’s disease
stage
Ann Arbor criteria
I
single lymph node region (LNR) or a single extralymphatic
site (ELS)
II
two or more LNRs on the same side of the diaphragm or a
solitary ELS and one or more LNRs on the same side of the
diaphragm
III
LNR on both sides of the diaphragm; with spleen
involvement or solitary involvement of an ELS or both
IV
diffuse involvement of the ELSs with or without lymph node
enlargement
presence of constitutional symptoms = B, absence = A
Staging: CAT scan, lymphangiogram, staging laparotomy
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Seminars for the 5th year
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Prof. MUDr. Jiří Horák
Th: depend on stage, bulk of disease, and the presence or absence of
symptoms. Radiation therapy alone is recommended in stage I – IIA; II B
– IIIA – chemotherapy + radiation; IIIB + IV – chemotherapy
MOPP: nitrogen mustard + vincristine + procarbazine + prednisone
Prognosis: stage IA and IIA – 5-year survival > 90%
IIIA
IIIB and IV
5-year survival > 80%
5-year survival > 50%
Th of relapses: combination chemotherapy or bone marrow
transplantation
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