بسم اهلل الرمحن الرحيم

Transcription

1 بسم اهلل الرمحن الرحيم

2 Definition Multiple myeloma is a neoplastic plasma cell dyscrasia (PCD) that generally produced a monoclonal immunoglobulin protein, characterized by a clinical pentad: (a) anemia; (b) a monoclonal protein in the serum or urine, or both, (c) abnormal bone radiographs and bone pain; (d)hypercalcemia; and (e) renal insufficiency or failure. With the exception of monoclonal gammopathy of undetermined significance (MGUS), it is the most common PCD. The underlying pathogenesis of the plasma cell malignancies is not well understood but is an area of active investigation. At present, according to World Health Organization and Revised European American Lymphoma Classification systems, there is only one category for multiple myeloma. Prognosis is best correlated with serum levels of Beta-2 microgobulin and C-reactive protein but also with the plasma cell labelling index.

3 Etiologic Factors 1) Radiation Exposures 2) WORKPLACE EXPOSURES 3) LIFESTYLE FACTORS 4) PRECURSOR MEDICAL CONDITIONS

4 PATHOGENESIS AND PATHOPHYSIOLOGY Normally, plasma cells make up a very small portion (less than 1%) of cells in the bone marrow. Myeloma plasma cells, however, have specific adhesion molecules on their surface allowing them to target bone marrow. After they enter the bone marrow, these adhesion molecules allow them to attach to structural cells called stromal cells. Once myeloma cells attach to bone marrow stromal cells, several interactions cause myeloma cells to grow (see figure):

5 Chemical messengers called cytokines are produced by both myeloma cells and stromal cells. These cytokines, such as interleukin 6 (IL-6), receptor for activation of NF_KB (RANK) ligand, and tumor necrosis factor (TNF), stimulate the growth of myeloma cells and inhibit (prevent) natural cell death (called apoptosis), leading to proliferation of myeloma cells and ultimately resulting in bone destruction. Myeloma cells also produce growth factors that promote angiogenesis, the creation of new blood vessels. These new blood vessels provide the oxygen and nutrients necessary for tumor growth. A growth factor called vascular endothelial growth factor (VEGF) plays a key role in angiogenesis. Angiogenesis helps the myeloma cells increase in number and begin to infiltrate the bone marrow, eventually comprising more than 10% of the cells present. Mature myeloma cells may fail to activate the immune system and may produce substances that decrease the body's normal immune response to a foreign body. Thus, the cells can grow unchecked.

6 Monoclonal Proteins The protein (also known as M component, myeloma protein, or spike) is a hallmark of the disease; 97% of myeloma patients have an intact Ig or a free light chain that can be detected by protein electrophoresis, immunoeelctrophoresis, or immunofixation studies of the serum urine. Those cases without a detectable monoclonal protein are referred to as nonsecretory myeloma. Monoclonal proteins have had a valuable role in the fields of immunology and molecular biology for distinguishing MGUS from myeloma and for calculating myeloma tumor burden and kinetics. M protein concentrations are used to stage myeloma patients and to document their response to treatment.

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9 Clinical Manifestations The symptoms of multiple myeloma may be nonspecific and include fatigue, bone pain, easy bruising and bleeding, recurrent infections, manifestations of anemia, hypercalcemia, lytic bone lesions, hyperviscosity, thrombocytopenia, and hypogammaglobulinemia. Weakness, infection, and weight loss, spontaneous bone pain & Renal insufficiency. Tumor fever is present in less than 1% of presenting patients.

10 Bone Disease

11 HEMATOLOGIC ABNORMALITIES Neoplastic myeloma cells may replace the normal hemopoietic tissue in the marrow. These cells consist predominantly of plasma cells exhibiting varying degrees of maturity. A larger cell with prominent nucleoli and scanty cytoplasm is usually present in small numbers. Such plasmablasts tend to increase with disease progression and may represent the dominant tumor cell population during the terminal disease phase. Tumor involvement of the marrow typically causes anemia, the degree of which appears related to tumor mass. Serum erythropoietin levels are relatively low for the degree of anemia present.

12 However, thrombocytopenia may develop subsequent to therapy or from autoimmune mechanisms. The antibody portion (Fab) of the myeloma protein may bind to fibrin during clotting and prevent fibrin aggregation. This probably represents the most common coagulopathy in patients with myeloma. In addition, hypercoagulable states may result from protein C deficiency, perhaps as a consequence of monoclonal immunoglobulins exhibiting anti- protein C activity. Lupus anticoagulants also have been reported in association with myeloma.

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14 Criteria For Diagnosis Of Plasma Cell Myeloma Major criteria Plasmacytomas on tissue biopsy Marrow plasmacytosis with>30% plasma cells Monoclonal globulin spike on serum electrophoresis>3.5g/dl for IgG or >2.0g/dl for IgA; 1.0g/24h of k or λ light-chain excretion on urine electrophoresis in the absence of amyloidosis. Minor criteria Marrow plasmacytosis 10-30% Monoclonal globulin spike present, but less than the levels defined above l. Lytic bone lesions Normal IgM<0.05 g/dl, IgA<0.1g/dl, or IgG<0.6g/dl

15 Therapy for symptomatic MM 1) Standard therapy Oral melphalan and prednisone VAD VMCP EDAP 2) Interferon Alpha 3) High dose therapy with autologous haemopoitic stem cell support 4) Allogenic stem cell transplantation.

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