November 10th, 2010

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WBC Neoplasms: OVERVIEW

WHITE CELL NEOPLASMS
--malignant proliferation dz is the most imp disorder of WBC
--two main types: lymphoid and myeloid
--lymphoid neoplasms incl: Hodgkin's lymphoma and non-Hodgkin's lymphoma
--myeloid neoplasms incl: proliferation of abn hematopoietic cells (AML, ALL, CML, CLL), myelodysplastic syndromes (MDS), histiocytoses, plasma cell dz (multiple myeloma)
--histological exam (biopsy) of lymph nodes or other involved tissue required for Dx
--in most lymphoid neoplasms, antigen receptor gene rearrangement precedes transformation, can be used to distinguish reactive and malignant lymphoid proliferations
--majority of lymphoid neoplasms are of B-cell origin (80-85%)**
--cause immune abnormalities
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Leukemias: Myelodysplasia, CLL, ALL, CML, AML, Hairy Cell

GENERAL NOTES:
--myeloid neoplasms incl: leukemias, myelodysplastic syndromes, histiocytoses, plasma cell dz
--malignant neoplasm of blood-forming tissue-->marrow replacement
--decreased apoptosis of cells --> increase in #'s
--ETIO: HTLV-1, oncogenes (p53), envir: EMF, benzene, radiation, x-rays, chemo drugs
--malignancy is found in 50% of pts with unexpected increased platelet counts (esp CML)
--acutes have immatures in PB, esp blasts
--chronics have more mature cells
--over 30% blasts in marrow usu means leukemia
--best way to differentiate btw B-cell and T-cell types: immunophenotyping
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Blood Diseases: Myeloproliferative

MYELOPROLIFERATIVE DISORDERS:
--caused by clonal expansion of pluripotent stem cell in bone marrow (BM) causing abnormal production of erythroid, myeloid, andmegakaryocytic precursors
--reflected in PB smear and CBC results
--multiple BM cell lines usu affected, but one cell line may dominate
--TYPES:
1. Polycythemia Vera
2. Myelofibrosis
3. Essential Thrombocythemia
4. Chronic Myelogenous Leukemia (CML)
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Plasma Cell Dyscrasias: Multiple Myeloma & Waldenstrom's Macroglobulinemia

A group of clinically and biochemically diverse diseases characterized by proliferation of ONE clone of plasma cells normally engaged in immunoglobulin production. PCD's account for 15% of WBC neoplasms. Typified by the presence of a monoclonal Ig or polypeptide subunit (fragment) in serum or urine. Monoclonal immunoglobin in the blood is referred to as "M component".

All are composed of terminally differentiated B cells, arise in the bone marrow, secrete whole Ab's or immunoglobulin fragments, cause bony destruction. Patients present with pain dt pathologic fractures.

Five types including related disorders:
1) Multiple Myeloma
2) Waldenstrom's macroglobulinemia
3) Heavy Chain dz
4) Primary or immunocyte-associated amyloidosis
5) MGUS = Monoclonal gammopathy of undetermined significance. MGUS is common in elderly pts and has no signs or symptoms.
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