What is plasma cell myeloma?

Plasma cell myeloma is medically known as myeloid plasmacytoma. The patients suffering from this disease are mainly elderly people. In the early stage of the disease, patients will feel bone pain, which is relatively mild in the early stage. As the disease progresses, the pain worsens and may extend to waist pain, back pain, and even pain in the chest and limbs. Severe cases may lead to hemiplegia and abnormalities in the sensory system. Bone marrow plasmacytoma is very harmful to the human body. It can destroy the body's immune function, leading to abnormal immune function, and thus causing various diseases throughout the body. In this regard, the editor will give you a detailed introduction to what plasma cell myeloma is, its specific causes and symptoms.

Myeloid plasmacytoma is a tumor caused by malignant proliferation of the B-lymphoplasmacytoma system. It is characterized by the malignant proliferation of abnormal plasma cells (or myeloma cells) in the bone marrow, which secrete certain humoral factors that cause abnormal activation of osteoclasts, resulting in osteolytic lesions, bone pain and bone destruction, anemia, renal damage, and immune dysfunction.

1. Causes and risk factors

The cause of the disease is currently unknown. Currently, humans only know some risk factors, such as high doses of ionizing radiation, chronic stimulation by antigenic substances and viral infection, and family factors have also been reported. This disease can also occur on the basis of chronic osteomyelitis, pyelonephritis, tuberculosis, chronic hepatobiliary system inflammation, autoimmune diseases, etc.

Pathogenesis

It is not clear at the moment. The significant increase in multiple myeloma in the elderly suggests that its basic process is related to immune function and aging. Immunosenescence is most evident in changes in the T cell lineage, which is consistent with thymic involution. The multi-step tumorigenic model is as follows: first, the thymus degenerates (the synovium may also degenerate), and loses control over the development of early B cells, including abnormal cytokine production; the second step is abnormal proliferation of multiple clones due to loss of normal regulation; the third step is that the clones that proliferate increase the chance of random gene mutations and cause malignant transformation.

3. Clinical manifestations

1. Clinical manifestations caused by direct infiltration and destruction of bones and other tissues by myeloma cells.

(1) Bone pain: It occurs in 60% to 70% of patients at first diagnosis and is the most common symptom. The disease progresses and worsens, often affecting the lower back, thorax, and limbs.

(2) Bone masses: They are often found in areas where red bone marrow is concentrated, such as the ribs, sternum, skull, and clavicle.

(3) Pathological fractures: mostly occur in the ribs, lower thoracic vertebrae and upper lumbar vertebrae.

(4) Neurological manifestations: Paraplegia, hemiplegia, nerve ending pain, paresthesia, etc. may occur due to compression or direct infiltration of the spine by myeloma.

(5) Infiltrative enlargement and functional impairment of extramedullary organs such as the liver, spleen, lymph nodes, and kidneys.

(6) Hypercalcemia: Bone destruction and bone absorption cause elevated blood calcium levels. Impaired renal function affects calcium excretion, and elderly myeloma patients who are forced to stay in bed for a long time and move less can aggravate hypercalcemia. It causes anorexia, nausea, vomiting, polyuria, severe cough, dehydration, and even impaired consciousness.

2. Clinical manifestations caused by myeloma cells producing abnormal plasma protein (M protein)

(1) Hyperviscosity: The amount of M protein in plasma increases, causing blood viscosity and slow blood flow, which can cause central nervous system hypoxia symptoms such as dizziness, blurred vision, tinnitus, and impaired consciousness, as well as extremity numbness and coronary artery insufficiency.

(2) Bleeding tendency: due to thrombocytopenia, the interaction between M protein and various coagulation factors causes coagulation mechanism and platelet dysfunction. Most of the bleeding is skin and mucous membrane bleeding.

(3) Renal insufficiency: This is often the cause of death in this disease. It may be caused by light chain protein deposition in the renal tubules, leading to nephron destruction, tumor cell infiltration, or secondary amyloidosis.

(4) Anemia: It occurs in 2/3 of newly diagnosed patients and is the main clue for diagnosing this disease, especially for elderly patients. Tumor cell infiltration leading to decreased erythropoiesis is the main cause of anemia. Anemia may be exacerbated by decreased erythropoietin levels, renal failure, increased blood volume, and shortened red blood cell lifespan.

(5) Infection: Due to abnormal immunoglobulin production, normal humoral immunity is deficient and neutropenia occurs, which makes people susceptible to lung and urinary tract infections and even sepsis.

3. A small number of other patients develop amyloidosis. Amyloid is often deposited in the tongue, kidneys, gastrointestinal tract, myocardium and peripheral nerves, causing functional disorders.

4. Laboratory examination of blood picture shows anemia; bone marrow picture shows an increase of more than 10% of morphologically abnormal plasma cells; increased erythrocyte sedimentation rate, immune dysfunction, hypermonoclonal globulinemia (M protein), hypercalcemia; increased urea nitrogen and creatinine in serum; X-ray examination shows osteoporosis in the early stage, and the typical lesions are round, clear-margin, perforated, and unequally sized osteolytic lesions, which are commonly found in the skull, pelvis, spine, femur, humerus, etc. Pathological fractures are mostly seen in the ribs, spine, clavicle, etc. (compression fractures).