Myeloma part 2
Marrow
In normal marrow, plasma cells are relatively sparse. In patients with myeloma, plasma cells are often present in abnormally large numbers. The myeloma cells accumulate in an uncontrolled manner (a sign of cancer), forming a tumor in the marrow. Sometimes, the myeloma cells collect in tissue and form a single mass (tumor) called a plasmacytoma. In most cases, however, this tumor spreads, usually in the marrow of many bones, including the ribs, backbone, pelvis, shoulder bones, breastbone, skull and others.
M Proteins (Monoclonal Immunoglobulins)
In myeloma, large amounts of a single type of protein, called M protein or monoclonal immunoglobulin, is made and secreted into the blood. The term monoclonal indicates the protein is derived from one cell population, the malignant plasma cells.
The body's normal process is for plasma cells to produce many types of proteins, called polyclonal immunoglobulins (antibodies), to protect the body against infection caused by invading viruses, bacteria, or other agents. By contrast, the production of M protein does not take place in response to an antigen, such as an infectious agent.
M protein can be measured in the blood. Changes in the amount of this protein usually parallel myeloma progression (increasing M protein concentration in the blood) or regression (decreasing M protein concentration in the blood).
Normal immunoglobulin is made up of of two heavy (larger) chains and two light (smaller) chains that are attached to each other. The normal immunoglobulin is too large to pass through the kidney, and so it is present in the blood, but not the urine.
The M protein in myeloma, like the normal immunoglobulin, is also made up of two heavy chains and two light chains attached to each other. However, in many cases of myeloma, the coordination of making and attaching light chains and heavy chains in the malignant plasma cells is lost and light chains (also called Bence Jones protein) leave the cell unattached. This fragment of immunoglobulin, the light chain, enters the blood, but is excreted rapidly in the urine (see Figure 2).
Figure 2. The Bence Jones protein (light chains) made by M protein are small enough to pass through the kidney and enter the urine, where they can be detected. When excreted in large amounts, Bence Jones protein can cause renal injury and kidney failure
Bone Destruction
Another special feature of malignant plasma (myeloma) cells is that they secrete chemicals (cytokines) that stimulate other cells that dissolve bone:
Bone is remodeled continuously. This remodeling is a coordinated effect of cells that dissolve bone (osteoclasts) and cells that lay down new bone (osteoblasts).
The chemicals secreted by plasma cells stimulate the bone-dissolving cells into marked overactivity. The bone-forming cells cannot keep up.
Holes (lytic spots) develop in the bone.
Bone is thinned (osteoporosis), and can be weakened sufficiently to break (fracture) with normal stresses of walking or lifting.
Slightly increased stresses of coughing and minor falls or injuries can also break the bones.
Symptoms and Signs
Bone pain is the most common early symptom of myeloma.
Most patients feel pain in the back or the ribs, but it can occur in any bone.
The pain is usually made worse by movement.
Patients fatigue more easily and often feel weak.
They may have a pale complexion from anemia, which is a common medical problem for patients with myeloma. Anemia may contribute to fatigue.
Patients may have repeated infections because antibodies to invading viruses, bacteria or other disease agents are not made efficiently or in adequate amounts.
A urinary tract, bronchial, lung, skin or other site of infection are often the first sign of the disease. In addition, recurrent infections may complicate the course of the disease.
Diagnosis
Myeloma may be discovered during a routine medical examination, before patients have symptoms of the disease. Approaches to diagnosis consist of:
Medical history and physical examination
Complete blood counts
Bone marrow examination
Bone imaging
M protein analysis
The diagnosis of myeloma depends on three principal findings. Taken together, these findings make it possible to for physicians to diagnose myeloma in a patient:
Increased numbers of malignant plasma cells (myeloma cells) are found when a bone marrow aspiration and biopsy are performed (usually from the hip bone).
Monoclonal immunoglobulin and Bence Jones (light chain) proteins are found in the blood or urine, respectively. In most patients with myeloma at least small amounts of light chains can be detected in the urine. In some myeloma patients blood tests do not show the characteristic increase or "spike" of M protein but the urine will have large amounts of light chains.
Thinning, holes or fractures of the bones that characterize myeloma are identified by imaging studies. Imaging studies include:
X-rays (skeletal surveys) and computerized tomography (CT) scans to identify any holes, breaks or thinning of the bones.
Magnetic resonance imaging studies (MRIs) and positron emission tomography (PET) scans to look for marrow changes and myeloma cell masses.
Physicians also order blood tests to obtain red cell, white cell and platelet counts (CBC or complete blood count) to measure the degree to which myeloma cells in marrow are affecting normal blood cell production.
Blood calcium is measured because the bone destruction causes calcium to leave bone and raise the blood levels.
The concentration of three proteins in the blood, lactic dehydrogenase, beta-2 microblobulin, and C-reactive protein, are obtained. These proteins are each an indirect measure of the size and growth rate of the myeloma tumors.
Tests that reflect kidney function (urea nitrogen and creatinine) and a urine examination (urinalysis) are usually performed.
In normal marrow, plasma cells are relatively sparse. In patients with myeloma, plasma cells are often present in abnormally large numbers. The myeloma cells accumulate in an uncontrolled manner (a sign of cancer), forming a tumor in the marrow. Sometimes, the myeloma cells collect in tissue and form a single mass (tumor) called a plasmacytoma. In most cases, however, this tumor spreads, usually in the marrow of many bones, including the ribs, backbone, pelvis, shoulder bones, breastbone, skull and others.
M Proteins (Monoclonal Immunoglobulins)
In myeloma, large amounts of a single type of protein, called M protein or monoclonal immunoglobulin, is made and secreted into the blood. The term monoclonal indicates the protein is derived from one cell population, the malignant plasma cells.
The body's normal process is for plasma cells to produce many types of proteins, called polyclonal immunoglobulins (antibodies), to protect the body against infection caused by invading viruses, bacteria, or other agents. By contrast, the production of M protein does not take place in response to an antigen, such as an infectious agent.
M protein can be measured in the blood. Changes in the amount of this protein usually parallel myeloma progression (increasing M protein concentration in the blood) or regression (decreasing M protein concentration in the blood).
Normal immunoglobulin is made up of of two heavy (larger) chains and two light (smaller) chains that are attached to each other. The normal immunoglobulin is too large to pass through the kidney, and so it is present in the blood, but not the urine.
The M protein in myeloma, like the normal immunoglobulin, is also made up of two heavy chains and two light chains attached to each other. However, in many cases of myeloma, the coordination of making and attaching light chains and heavy chains in the malignant plasma cells is lost and light chains (also called Bence Jones protein) leave the cell unattached. This fragment of immunoglobulin, the light chain, enters the blood, but is excreted rapidly in the urine (see Figure 2).
Figure 2. The Bence Jones protein (light chains) made by M protein are small enough to pass through the kidney and enter the urine, where they can be detected. When excreted in large amounts, Bence Jones protein can cause renal injury and kidney failure
Bone Destruction
Another special feature of malignant plasma (myeloma) cells is that they secrete chemicals (cytokines) that stimulate other cells that dissolve bone:
Bone is remodeled continuously. This remodeling is a coordinated effect of cells that dissolve bone (osteoclasts) and cells that lay down new bone (osteoblasts).
The chemicals secreted by plasma cells stimulate the bone-dissolving cells into marked overactivity. The bone-forming cells cannot keep up.
Holes (lytic spots) develop in the bone.
Bone is thinned (osteoporosis), and can be weakened sufficiently to break (fracture) with normal stresses of walking or lifting.
Slightly increased stresses of coughing and minor falls or injuries can also break the bones.
Symptoms and Signs
Bone pain is the most common early symptom of myeloma.
Most patients feel pain in the back or the ribs, but it can occur in any bone.
The pain is usually made worse by movement.
Patients fatigue more easily and often feel weak.
They may have a pale complexion from anemia, which is a common medical problem for patients with myeloma. Anemia may contribute to fatigue.
Patients may have repeated infections because antibodies to invading viruses, bacteria or other disease agents are not made efficiently or in adequate amounts.
A urinary tract, bronchial, lung, skin or other site of infection are often the first sign of the disease. In addition, recurrent infections may complicate the course of the disease.
Diagnosis
Myeloma may be discovered during a routine medical examination, before patients have symptoms of the disease. Approaches to diagnosis consist of:
Medical history and physical examination
Complete blood counts
Bone marrow examination
Bone imaging
M protein analysis
The diagnosis of myeloma depends on three principal findings. Taken together, these findings make it possible to for physicians to diagnose myeloma in a patient:
Increased numbers of malignant plasma cells (myeloma cells) are found when a bone marrow aspiration and biopsy are performed (usually from the hip bone).
Monoclonal immunoglobulin and Bence Jones (light chain) proteins are found in the blood or urine, respectively. In most patients with myeloma at least small amounts of light chains can be detected in the urine. In some myeloma patients blood tests do not show the characteristic increase or "spike" of M protein but the urine will have large amounts of light chains.
Thinning, holes or fractures of the bones that characterize myeloma are identified by imaging studies. Imaging studies include:
X-rays (skeletal surveys) and computerized tomography (CT) scans to identify any holes, breaks or thinning of the bones.
Magnetic resonance imaging studies (MRIs) and positron emission tomography (PET) scans to look for marrow changes and myeloma cell masses.
Physicians also order blood tests to obtain red cell, white cell and platelet counts (CBC or complete blood count) to measure the degree to which myeloma cells in marrow are affecting normal blood cell production.
Blood calcium is measured because the bone destruction causes calcium to leave bone and raise the blood levels.
The concentration of three proteins in the blood, lactic dehydrogenase, beta-2 microblobulin, and C-reactive protein, are obtained. These proteins are each an indirect measure of the size and growth rate of the myeloma tumors.
Tests that reflect kidney function (urea nitrogen and creatinine) and a urine examination (urinalysis) are usually performed.
posted by TM at 11:51 AM
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