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Chapter 21 Monoclonal Gammopathies

Chapter 21 Monoclonal Gammopathies. Wu Jianmin. GUIDELINES FOR EVALUATING MONOCLONAL GAMMOPATHIES. 1.Which Patients Should be Evaluated for the Presence of an M-Protein 2.What Types of Specimens Should be Studied, and How Often Should They be Used to Follow Patients

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Chapter 21 Monoclonal Gammopathies

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  1. Chapter21 Monoclonal Gammopathies WuJianmin

  2. GUIDELINES FOR EVALUATING MONOCLONAL GAMMOPATHIES 1.Which Patients Should be Evaluated for the Presence of an M-Protein 2.What Types of Specimens Should be Studied, and HowOften Should They be Used to Follow Patients with M-Proteins 3.Which Laboratory Methods should be used to Detect, Identify, and Follow M-Proteins

  3. DISEASE STATES 1.Myeloma 2.Immunoglobulin Isotypes in Multiple Myelorna 3.Waldenström's Macroglobulinemia 4.Monoclonal Gammopathy Of Undetermined Significance. 5.B-Cell Neoplasms 6.Amyloidosis

  4. A monoclonal gammopathy is the protein product of a single clone of plasma cells. Although the term "monoclonal gammopathy" often has been used to designate the proteins produced by the malignant cells in multiple myeloma and other B-cell lymphoproliferative lesions, such as Waldenström's macroglobulinemia, a monoclonal gammopathy also may be the product of a "regulated" cell.

  5. Factors to consider when evaluating an M-protein include the quantity of the M-protein, the fluid in which it is found (serum versus urine), and the chemical type of the M-protein (light chains will more likely be found in the urine than in the serum).

  6. The term M-protein is used in the literature to describe the monoclonal gammopathy. Although it has been variously used for "monoclonal component, mveloma prorein, and macroglobulin protein," the recently published guidelines for evaluating monoclonal gammopathies recommend the use of the term "M-protein".

  7. Which Patients Should be Evaluated for the Presence of an M-Protein

  8. M-proteins are found in the serum and/or urine of patients with a wide variety of clinical conditions. The occurrence and clinical symptoms of these conditions vary widely (Table 21-1).

  9. TABLE 21-1 CONDITIONS ASSOCIATED WITH THE PRESENCE OF AN M-PROTEIN Multiple myeloma Back pain, osteolytic lesions, fatigue, elevated sedimentation rate, nephrotic syndrome, infections, anemia, elevated calcium Waldenström's Fatigue, elevated sedimentation rate, macroglobulinemia dizziness, anemia, hyperviscosity B-Lymphoproliferative Fatigue, anemia, lymphadenopathy, disorders lymphocytosis Amyloid (AL), light chain Nephrotic syndrome, congestive deposition disease heart failure,carpal tunnel syndrome Neuropathy and M-protein Peripheral sensory and/or motor neuropathy Monoclonal gammopathy of No symptoms related to the M-protein undetermined significance (MGUS) Condition Clinical Features

  10. Traditionally, the size of the M-protein has been helpful in determining the significance for the patient. Typically, a large quantity of M-protein (greater than 2 G/dL) is more likely to be associated with myeloma, whereas, a small quantity of M-protein may be associated with monoclonal gammopathy of undetermined significance (MGUS) . Yet, several important conditions associated with small quantities of M-proteins may be overlooked if these M-proteins are not recognized (Table 21-2).

  11. TABLE 21-2CONDITIONS WITH RELATIVELY SMALL QUANTITIES OF M-PROTEIN IN SERUM Condition Associated Feature Light chain disease 15% of cases of multiple myeloma are light chain disease Amyloid (AL) 20% have multiple myeloma or Waldenström's macroglobulinemia Heavy chain disease Alpha chain disease is rare in United States Gamma chain disease is associated with B-lymphoproliferative disorders M-protein associated neuropathy Must do Immunofixation of serum to rule out Cryoglobulin type II Associated with Hepatitis C Solitary plasmacytoma Tiny or no M-protein in serum B-Lymphoproliferative disorder Often with overall gamma suppression MGUS The most common cause of serum M-proteins

  12. What Types of Specimens Should be Studied, and How Often Should They be Used to Follow Patients with M-Proteins

  13. The initial evaluation of a patient with clinical features suggesting the presence of an M-protein should include a serum and urine electrophoresis using high-resolution methods (Fig. 21-1).

  14. Fig. 21-1. Specimens and evaluation for detecting monoclonal gammopathies.

  15. If the serum protein electrophoresis is negative, and there is a low index of suspicion, one may wish to look for other causes of the symptoms before performing an immunofixation (IFE). However, if the clinical suspicion is high, an IFE should be performed even when no M-protein is seen on the screening electrophoresis.

  16. If an M-protein is found on the screening electrophoresis, an IFE must be performed to identify the M-protein. This identification serves several purposes. First, it rules out a false positive due to some other protein that may mimic an M-protein on serum protein electrophoresis (Table 21-3).

  17. Table 21-3．proteins that may mimic an M-protein Fibrinogon C3 Variant Transferrin variant Beta-1 lipoprotein Antibiotic band on capillary zone electrophoresis

  18. Second, because IFE is more sensitive than screening electrophoresis, it may identify a second M-protein (often a monoclonal free light chain that accompanies the intact molecule in the serum). Third, it identifies the M-protein for comparison with subsequent samples from the patient. If there is no change in the migration of the identified M-protein on subsequent samples, there is no need to perform further IFE studies.

  19. For serum, the best measurement of the M-protein is achieved by performing high-resolution electrophoresis and measuring the amount of protein below the spike (Fig. 21-2).

  20. Fig.21-2. Capillary zone electropherogram with M-protein. M-proteins should be measured integrating the area under the peak.

  21. For the urine, it is important to follow the monoclonal free light chains and not the intact M-protein immunoglobulin that may be found in the urine. The prognosis and threat to the kidney is mainly due to the amount of monoclonal free light chain and not due to the intact M-protein.

  22. The panel agreed that the term "Bence Jones protein" has been somewhat confusing in this regard. Bence Jones protein only refers to the monoclonal free light chains, not to the intact monoclonal immunoglobulins.

  23. Which Laboratory Methods should be used to Detect, Identify, and Follow M-Proteins

  24. The panel was unanimous that the laboratory should use a high-resolution electrophoretic method in the initial evaluation of serum and urine. A high-resolution method is one that permits a crisp separation of transferrin and C3 in the beta region (Fig. 21-3).

  25. Fig.21-3. high-resolution electrophoresis with M-protein (top).normal (middle). And polyclonal patterns. The gel or CZE pattern should provide crisp separation of the beta-1 (transferrin) band from the beta-2 (C3) band.

  26. immunofixation with an IgA kappa M-protein. Note the small M-protein band (arrow) in the SPE lane. The IgA and kappa restrictions are obvious.

  27. DISEASE STATES

  28. Myeloma Multiple myeloma is the most common malignant cause for the presence of an M-protein in serum or urine. This disease is because of a malignant proliferation of a clone of B lymphocytes that manifests predominantly as plasma cells. Note that multiple myeloma often is considered to be a condition of malignant plasma cells. In fact, the malignancy involves the entire B-cell lineage but manifests mainly as malignant plasma cells.

  29. Immnunoglobulin Isotypes in Multiple Myelorna The isotypes of immunoglobulins seen in multiple myeloma largely reflect their prevalence in normal serum. IgG myeloma proteins predominate. They are almost always monomers weighing 160,000 daltons. It is rare that IgG myeloma proteins produce significant problems with hyperviscosity. IgE myeloma is extremely rare and can occur as monomers or as polymers with variable molecular weight.

  30. IgA myeloma may be difficult to diagnose on occasion because IgA tends to migrate in the P region. Therefore, early in its course, the other beta region bands may mask the IgA myeloma. C3, transferrin, or fibrinogen from an inadequately clotted sample of blood or an inadvertently examined sample of plasma may obscure the presence of an IgA myeloma M-protein.

  31. IgD myelomas also may be missed because the amount of M-protein may be relatively small. If one is using the older five-band electrophoresis techniques, a normal alpha 2 or beta region band may hide the small IgD component. Also, as discussed later, when radial immunodiffusion plates perform quantification, at least two dilutions of the patient's serum must be performed to avoid antigen excess.

  32. Alpha heavy-chain disease is extremely uncommon in the western world. In the Middle East and Mediterranean regions, an unusual disease called a heavy-chain disease occurs. The tissue distribution of the plasma cells in this lesion roughly parallels that for the normal distribution of IgA along the gastrointestinal tract and other mucosal surfaces.

  33. Waldenström's Macroglobulinemia Patients with Waldenström's macroglobulinemia suffer from complications of hyperviscosity from the presence of large amounts of circulating IgM. IgM almost always circulates as a pentamer (19S). Therefore, when one develops a monoclonal proliferation of cells producing IgM, the increased concentration of large proteins in the blood disturbs the normal circulation hemodynamics, resulting in the hyperviscosity syndrome. This causes a variety of neurologic complaints, cardiac insufficiency, and vascular insufficiency throughout the body.

  34. Monoclonal Gammopathy Of Undetermined Significance In older textbooks, the term for this section would have been "benign monoclonal gammopathies." By this term, he referred to individuals who have a monoclonal component demonstrated in the serum, but who lack other key features for diagnosing a malignant monoclonal gammopathy. These patients are not anemic, they do not have lytic lesions, and they do not have elevated serum calcium or serum enzymes.

  35. B-Cell Neoplasms A variety of B-cell neoplasms have been associated with monoclonal gammopathies. In fact, the majority of these patients have a monoclonal gammopathy in either their serum or their urine when high-resolution electrophoresis and immunofixation are combined to study these samples. Monoclonal gammopathies also have been demonstrated in patients with Burkitt's lymphoma and B-cell ALL.

  36. Amyloidosis About 4% patients with plasma cell proliferation will have amyloid deposition in their tissues. There are two major biochemical types of amyloid. One consists of an immunoglobulin light chain and is termed AL. The second is composed of protein A and is termed AA.

  37. Thanks!

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