I. Basic knowledge of multiple myeloma
1.What is multiple myeloma? What is the cause of the disease?
Multiple myeloma is a malignant proliferative tumor that originates from plasma cells in the blood system. Myeloma cells clonally proliferate in the bone marrow, causing osteolytic bone destruction; at the same time, myeloma cells secrete large amounts of monoclonal immunoglobulins, and excessive immunoglobulin light chains are excreted in the urine, which is called proteinuria of the week. It is often associated with anemia, renal impairment and extramedullary plasmacytoma. The exact pathogenesis of myeloma is still unclear, but with the development of various biotechnologies, the understanding of the pathogenesis of myeloma has advanced. The development of myeloma may be related to chromosomal abnormalities caused by genetic mutations. Baoan Chen, Department of Hematology, Zhongda Hospital, Southeast University
2. Is multiple myeloma contagious?
Although certain genetic abnormalities are found in some myeloma patients, most of these abnormalities are acquired by mutations, so they are not generally contagious to others or their offspring.
3.What are the types of multiple myeloma? How are they differentiated?
According to the different monoclonal immunoglobulins secreted by multiple myeloma cells, multiple myeloma can be divided into the following 8 types: IgG, IgD, IgA, IgE, IgM, light chain, biclonal and non-secreting. IgG, IgA, light chain and IgD types are more common.
4.Is multiple myeloma fatal? How long can I live if I have it?
Multiple myeloma is still an incurable disease, but since autologous stem cell transplantation has been successfully applied to multiple myeloma patients, the efficacy and survival have been greatly improved. The successful use of immunomodulatory drugs, especially proteasome inhibitors in the 21st century, in myeloma patients since the late 1990s has significantly improved overall long-term survival.
Multiple myeloma is a heterogeneous disease and the response to treatment, the occurrence of complications and survival vary greatly from patient to patient. Survival is highly variable, from a few months in short cases to more than 10 years in long cases.
5.Who is prone to multiple myeloma?
The incidence rate of multiple myeloma in China is about 1/100,000, which is lower than that in western industrialized countries (about 4/100,000), and the age of onset is mostly between 50-60 years old, and those under 40 years old are less common.
Therefore, older people, especially those with a family history of tumor or tumor susceptibility factors (such as special occupations), are relatively more likely to develop multiple myeloma.
6.Can special occupations cause multiple myeloma?
Ionizing radiation has been shown to be a risk factor for acute myeloid leukemia, but there is no evidence of a role for chronic low-dose radiation exposure in the development of multiple myeloma. With modern industrial protection and strict regulations, occupational radiation exposure is unlikely to significantly increase the incidence of multiple myeloma. Moderated studies of organic solvents, herbicides, and other chemical agents have also failed to find a role in the development of myeloma.
7. Pathogenesis of multiple myeloma
The diverse clinical manifestations of MM are caused by the uncontrolled proliferation and infiltration of malignant clonal plasma cells and their secretion of large amounts of monoclonal immunoglobulins: overproliferation of tumor cells in the bone marrow at the primary site, leading to suppression of bone marrow hematopoietic function; extensive infiltration of tumor cells may involve lymph nodes, spleen, liver, respiratory tract and other sites, causing dysfunction of the involved tissues and organs: some factors secreted by tumor cells The presence of a large amount of monoclonal immunoglobulin secreted by tumor cells in the blood causes increased blood viscosity and dysfunction of coagulation factors, while the excretion of excessive light chains from the kidneys causes kidney damage and the deposition of light chains in tissues and organs causes amyloidosis damage. secondary infections.
Examination and diagnosis of multiple myeloma
1.How to diagnose multiple myeloma
The diagnosis should be made by combining the percentage of myeloma cells in bone marrow smear examination, the amount of M protein in blood or urine, osteolytic damage in X-ray examination and other indicators with the clinical manifestations of patients.
Generally, the diagnosis of multiple myeloma should be considered when there is an increase of plasma cells in bone marrow (>30%), the amount of M protein in blood or urine is greater than 35g/L or 1g/24h respectively, and there is osteolytic damage on X-ray.
2.Clinical staging criteria of multiple myeloma
The clinical stage reflects the early and late course of the disease, and the early and late course of MM mainly depends on the total number of myeloma cells in the patient’s body (tumor load), when the number of tumor cells is limited, it does not cause clinical symptoms, and the patient may not notice it, which is called the pre-clinical stage, and this stage is usually 1 to 2 years, and the pre-clinical stage of a few cases can be 4 to 5 years or longer. When the total number of tumor cells is ≥1×1011, the clinical symptoms will begin to appear, and the disease will gradually worsen as the number of tumor cells increases.
3.Pathological typing of multiple myeloma
(1) IgG type: The most common type, accounting for about 50% of MM, with typical clinical manifestations of MM
(2) IgA type: IgA type accounts for about 15%-20% of MM, in addition to the general manifestations of MM, IgA easily aggregates into multimers and causes hyperviscosity, and is prone to hypercalcemia and hypercholesterolemia, etc.
(3) Light chain type: Its monoclonal immunoglobulin is monoclonal to κ chain or monoclonal to λ chain, while heavy chain is absent, this type accounts for about 15%-20% of MM, this type of tumor cells are often poorly differentiated, proliferate rapidly, bone destruction is common, and renal function damage is more severe.
(4) IgD type: It accounts for about 8% to 10% of MM. In addition to the general manifestations of MM, it is characterized by relatively young age of onset, extramedullary infiltration, and relatively frequent osteosclerotic lesions.
(5) IgM type: rare, accounting for only about 1% of MM, in addition to the general clinical manifestations of MM, because of its larger molecular weight (molecular weight 950000) and easy to form pentamers and increase blood viscosity, so prone to high viscosity syndrome is its characteristics.
(6) IgE type:, this type is rare
(7) biclonal or polyclonal type: this type is rare, accounting for less than 1% of MM
(8) non-secretory type: this type accounts for about 1% of MM, patients have significant proliferation of plasma (tumor) cells in the bone marrow, bone pain, bone destruction, anemia, reduced normal immunoglobulin, prone to infection and other typical clinical manifestations of MM, but no M component in the serum, no monoclonal light chain in the urine (urine Ben – week protein negative).
4.Differential diagnosis of multiple myeloma
The misdiagnosis rate of this disease is very high. Patients may be misdiagnosed as respiratory infection, nephritis, bone disease and delayed because of fever, urine change, back and leg pain. In elderly patients with renal damage along with bone pain or anemia that does not parallel renal insufficiency (renal anemia parallels the degree of renal insufficiency), tests related to myeloma should be performed. Low back pain is one of the main symptoms of multiple myeloma and is often one of the main complaints of patients seeking medical attention, who may choose general surgery, orthopedic consultation. It is often misdiagnosed as lumbar strain, lumbar spine tuberculosis, osteoporosis and other diseases, which should be distinguished from reactive plasmacytosis, monoclonal immunoglobulinemia of undetermined significance (MGUS) and other M-protein producing diseases such as chronic infection, chronic liver disease and autoimmune diseases.
5.X-ray examination of multiple myeloma
X-ray examination is of great significance in the diagnosis of this disease, which has the following four types of X-ray manifestations.
(1) Diffuse osteoporosis: vertebrae, ribs, pelvis, and skull are often obvious, and also seen in the long bones of the limbs.
(2) Osteolytic lesions: multiple round or oval shaped with clear sharp chisel-like osteolytic lesions are the typical X-ray signs of the disease, commonly found in the skull, pelvis, ribs, vertebrae, and occasionally in the bones of the extremities.
(3) Pathological fractures: most commonly seen in the lower thoracic and upper lumbar spine, mostly as compression fractures, followed by the ribs, clavicle, pelvis, and occasionally in the bones of the extremities.
(4) Osteosclerosis: this lesion is rare.