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21 Cards in this Set

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General features of myeloproliferative disorders
Neoplastic event begins at level of pluripotent stem cell
-- each of the major cell lines are involved, some w/ more prolif than others

Hallmark is proliferation
-- increased, autonomous production of hematopoietic cells
-- hypercellular bone marrow

Increased cell counts in peripheral blood
-- leukocytosis
-- thrombocytosis
-- polycythemia
How are myeloproliferative diseases classified?
They are classified by cell line:

myeloid --> chronic myelocytic leukemia

erythroid --> polycythemia vera

megakaryocytic --> essential thrombocythemia

"fibroblasts" --> chronic idiopathic myelofibrosis (fibroblasts themselves are not neoplastic, just a prolif of the cell type)
What other disorders must we distinguish myeloproliferative d/o's from ?
MPD must be distinguished from benign cell proliferations that can closely mimic the MPD.
MPD -- has MATURE cells which can disting from benign prolif

MPD -- splenomegaly, absolute basophilia, increased serum B12

Clinical presentation is less acute than acute leukemia, and sometimes the pts may be asymptomatic
What are the myeloproliferative disorders?
Chronic Myelocytic Leukemia (CML)

Chronic Idiopathic Myelofibrosis (CIM)

Polycythemia Vera

Essential Thrombocythemia

OTHERS:
chronic neutrophilic leukemia
chronic eosinophilic leukemia
chronic myeloprolif disease, unclassifiable
Clinical findings in CML?
Chronic myelogenous leukemia

Range of incidence is 25-60, byt also accounts for 15% of all leukemias in pediatric age group

Symptoms of anemia and hypermetabolism
-- weakness, fatigue
-- weight loss, anorexia

Splenomegaly may be present
-- abdominal pain and increasing abdominal girth

Pts may be asymptomatic and found to have abnormal cell count on routine lab testing
Physical findings in CML?
May find splenomegaly

May be normal exam
Lab findings in CML?
WBC:
-- markedly elevated, usually >50K, and frequently >100K
-- differential shows myeloid precursors including blasts
-- absolute basophilia is almost always present

RBC:
-- usually mild anemia, but may be normal

PLATELET COUNT:
-- frequently count but may be normal or decreased

BONE MARROW:
-- nearly 100% cellular (50% is normal for adults)
-- predominance of myelopoiesis showing maturation
-- ratio of myeloid/erythroid cells is increased, frequently 10:1 (normal is 3:1)

LAP:
-- markedly decreaseed

CYTOGENETICS:
-- >90% of cases will have "Philadelphia translocation," t(9;22)(q34;q11.2) involving genes ABL at 9q34 and BCR at 22q11.2
-- BCR/ABL forms new hybrid gene that produces a protein of 210kD size
-- t(9;22) is present in all hematopoietic cells excluding a few lymphocytes
Prognosis of CML?
Most patients will succumb to a blast crisis --> a prolif of blasts replacing the maturation in the BM
-- occurs 3-5 yrs after initial presentation
-- at time of crisis, additional chrom aberrations can be seen

BM transplant is treatment of choice in the chronic phase

Some pts will respond to alpha-interferon and show extended remission

New therapy w/ Imatinib Mesylate (Gleevec), an inhibitor of specific protein tyrosine kinases, show promise for improved prognosis
Differential for CML?
Leukemoid rxn

Other MPD

Chronic myelomonocytic leukemia
Clinical findings in CIM?
Predom older adults >50

May be asymptomatic or present w/ signs/symptoms of anemia and splenomegaly

Splenomegaly is part of the disease process due to the myeloid metaplasia

**disorder is also called agnogenic myeloid metaplasia, and myelofibrosis w/ myeloid metaplasia (MMM)
Lab findings in CIM?
WBC:
-- usually elevated but <25K
-- can be normal or decreased
-- Differential shows myeloid cells at all stages of maturation, including blasts and presence of nucleated RBCs (leukoerythroblastosis)

RBC:
-- anemia is almost always present
-- anisopoikilocytosis, especially w/ tear drop shaped cells

PLATELETS:
-- usually normal or elevated
-- large hypogranular
-- sometimes circulating micromegakaryocytes

BONE MARROW:
-- marrow is hypercellular, but w/ a diffuse background fibrosis making it "inaspirable"
-- clusters of megakaryocytes seen

CYTOGENETICS:
-- 50% may have chrom aberrations, but none are diagnostic
Prognosis of CIM?
Pts usually survive 5-10yrs

Approx 10-15% will evolve into blast crisis

Most will have gradual replacement of marrow hematopoiesis w/ dense fibrosis and succumb to problems of marrow failure
-- severe anemia
-- hemorrhage
-- infection

Treatment is mainly supportive, as no effective "curative" treatment
-- BM transplant performed in few cases
Differential for CIM?
"Leukoerythroblastosis"
1. marrow stress --> infection, hemorrhage, hemlolysis

2. myelophthisis --> metastatic tumor or granulomas in BM

3. Other myeloprolif d/o's
Clinical findings in polycythemia vera?
Older adults >50; median age is 60

Signs and symptoms of increased red cell mass:
-- plethora
-- cyanosis
-- HTN
-- headaches
-- dizziness
-- abdom pain

Increased blood volume together w/ abnormally fxning platelets leads to problems of thrombosis AND hemorrhage
Lab findings in polycythemia vera?
WBC:
-- usually mildly elevated at time of dx, <25K, but may be normal

RBC:
-- elevated
-- HCT >55% (erythrocytosis)
-- normal morphology, unless coincident iron deficiency

PLATELETS:
-- normal or elevated
-- may have abnormal fxn

BONE MARROW:
-- hypercellular w/ increase of all hematopoietic precursors

ERYTHROPOIETIN:
-- serum levels DECREASED

CYTOGENETICS:
-- 50% of cases may show chrom aberrations but none are diagnostic
Prognosis of polycythemia vera?
Pts usually survive 10-15yrs

Approx 5-10% will bave blast crisis

Most enter a "spent phase" of marrow failure

Treatment aimed at decreasing RBC mass
Differential Dx of polycythemia vera?
RELATIVE POLYCYTHEMIA
-- dehydration
-- spurious

ABSOLUTE POLYCYTHEMIA
Primary:
-- Polycythemia Rubra Vera
Secondary:
Appropriate
-- high altitude
-- cardio-pulmonary disease
-- hemoglobinopathies
Inappropriate
-- renal cyst
-- neoplasms
Clinical findings in essential thrombocytopenia?
Least common -- predominantly older adults

Patients will have problems related to hemorrhage AND thrombosis
Lab findings in essential thrombocytopenia?
WBC:
-- normal or elevated

RBC:
-- usually mild to moderate anemia

PLATELET COUNT:
-- >600K and frequently is >1million
-- morphology may be normal, or may have some large and or hypogranular platelets

BONE MARROW:
-- hypercellular w/ increased megakaryocytes
-- some may be large w/ immature nuclei
-- may be in clusters
Prognosis of essential thrombocytopenia?
Patients are usually older and survival ranges from 10-15yrs
Differential Dx of essential thrombocytopenia?
Other causes of thrombocytosis:
-- chronic inflamm D/O's
-- TB
-- Various neoplasms
-- other MPD