Multiple myeloma is a cancer of plasma cells leading to increased proliferation of these malignant cells and overproduction of M protein. It is a cancer of bone marrow involving about 10% of the bone marrow. Since plasma cells are responsible for the production of immunoglobulins, multiple myeloma is characterized by overproduction of immunoglobulin G, immunoglobulin A and light chains. Since it is a bone marrow cancer, its major effect is in the bones, as it leads to widespread destruction of bones with severe osteoclastic activities causing hypercalcemia and anemia. The overcrowding of the bone marrow with malignant plasma cells inhibits the movement of leucocytes, red blood cells and platelets from bone marrow to the blood leading to widespread leucocytopenia, anemia and thrombocytopenia.
What Are The First Signs Of Multiple Myeloma?
Most of the times, multiple myeloma is diagnosed after a routine blood test done for unknown problems. Other times it is diagnosed subsequent to a pathological fracture. The common presenting signs and symptoms of multiple myeloma are weakness, infection, anemia, bone pain, pathological fractures, hypercalcemia, hyperviscosity, spinal cord compression and renal failure.
Pathological fracture and bony lesions are a common event in multiple myeloma. 70% people have a complaint of bone pain and on examination bony tenderness may not be found. Bone pain is very common in the lower back area, hips, other long bones, and skull. The bony fracture is more common in the lower extremity than in the upper extremity. (1)
Low blood count leads to anemia, leucopenia, and thrombocytopenia. Anemia is the reduction in red blood cells, which will cause symptoms of weakness, dizziness and exertional shortness of breath. Leucopenia is due to reduced white blood cells and will cause increased chances of infection. Thrombocytopenia is due to reduced platelet count and will cause easy bruising and severe bleeding.
Infections are also very common in multiple myeloma subsequent to decreased immunity and leucopenia. Commonly involved organisms are pneumococcus, herpes zoster, and hemophilus. Meningitis due to pneumococcal or meningococcal infection is common in multiple myeloma patients.
Spinal cord compression is another sign that may lead to symptoms of weakness, numbness, paresthesias in the lower extremity and back pain. In severe cases it may lead to dysfunction and paralysis.
Hypercalcemia is another finding that may lead to symptoms of nausea, polydipsia, polyuria, constipation, bone pain, muscle cramps, confusion, somnolence and kidney stones.
Hyperviscosity due to malignant plasma cells leads to symptoms of generalized malaise, fever, infection, paresthesias, sensory loss, somnolence, seizures, confusion, headache, hazy vision, papilledema, retinal hemorrhage, coronary ischemia, easy bruising and purpura.
Bleeding may be due to thrombocytopenia and hyperviscosity. Thrombocytopenia is associated with ecchymosis. Epistaxis is a common presenting symptom. It may lead to anemia that causes weakness. Complications of hyperviscosity include myocardial ischemia or infarction and stroke.
Amyloid deposition has a lot of sequalae including neurological findings of neuropathy, carpal tunnel syndrome, myopathy, soft tissue masses, hepatomegaly, splenomegaly, cardiomegaly, macroglossia, skin lesions, purpura, and shoulder pad sign. Shoulder pad sign is bilateral swelling (hard and rubbery) of the shoulder joints due to amyloid deposition. Macroglossia is also due to amyloid deposition in the tongue. Skin lesions are waxy papules or nodules that are commonly found in ears, lips and torso. Renal failure may also be secondary to amyloid deposition in kidneys.
Multiple myeloma is responsible for about 10% of all hematologic cancers. It is more common in men than in women with a male to female ratio of 3:2. Multiple myeloma is a disease of adults and is hardly ever seen in younger patients. The median age of patients for multiple myeloma is 68 years for men and 70 years for women. It is more common in black and Hispanic people.
The exact cause of multiple myeloma is yet to be established. However, various factors, such as genetics, environmental, occupational, radiation, infection (human herpes virus 8), chronic inflammation and monoclonal gammopathy of unknown significance (MGUS) have been implicated.