Multiple myeloma and leukemia are both distinct types of cancer affecting the blood and bone marrow. While both conditions involve the uncontrolled growth of abnormal cells within the body’s blood-forming system, they originate from different cell types and manifest with unique characteristics. This article aims to explain the fundamental differences between multiple myeloma and leukemia.
Multiple Myeloma: A Plasma Cell Cancer
Multiple myeloma is a cancer of plasma cells, a type of white blood cell normally found in the bone marrow that produces antibodies. In multiple myeloma, these abnormal plasma cells multiply uncontrollably within the bone marrow.
Cancerous plasma cells produce large amounts of a dysfunctional antibody, called an M-protein. The accumulation of these cells and proteins leads to serious health issues, including bone damage (lytic lesions), impaired kidney function, and elevated blood calcium (hypercalcemia).
Excessive myeloma cell growth in the bone marrow crowds out healthy blood-forming cells. This displacement leads to anemia, a condition characterized by a reduced number of red blood cells. Patients may experience fatigue and weakness as a consequence of this anemia.
Leukemia: Cancers of Blood-Forming Cells
Leukemia refers to cancers that begin in the bone marrow’s immature blood-forming cells, which normally develop into white blood cells, red blood cells, and platelets. In leukemia, these cells become cancerous and multiply abnormally.
The uncontrolled production of abnormal white blood cells (leukocytes) interferes with the bone marrow’s ability to produce healthy blood cells, leading to deficiencies in red blood cells, platelets, and functional white blood cells. Leukemia is categorized by its progression (acute or chronic) and the cell type involved (myeloid or lymphoid).
The displacement of healthy blood cells by leukemic cells results in various complications. Patients often experience impaired immune function, making them more susceptible to infections. Anemia, leading to fatigue and pallor, and low platelet counts, causing easy bruising and bleeding, are also common.
Key Differences: Myeloma vs. Leukemia
The fundamental difference between multiple myeloma and leukemia is their cell of origin. Myeloma arises from plasma cells, which are mature antibody-producing B-lymphocytes. Leukemia, however, originates from earlier, immature myeloid or lymphoid stem cells in the bone marrow, before they fully mature.
Their primary locations also differ. Myeloma primarily affects the bone marrow, causing skeletal damage and kidney complications from M-proteins. Leukemia primarily affects the bone marrow and circulating blood, often spreading to organs like the spleen, liver, and lymph nodes.
Clinical presentations reflect these distinctions. Myeloma often causes bone pain (especially in the back or ribs) from lesions and fractures, fatigue, and kidney problems. Leukemia symptoms relate to a lack of normal blood cells, including fatigue, frequent infections, easy bruising or bleeding, and sometimes enlarged spleen or liver.
How They Are Diagnosed Differently
Diagnosis for both is tailored to their specific origins. For myeloma, a bone marrow biopsy confirms abnormal plasma cells. Blood and urine tests detect M-proteins, and imaging (X-rays, MRI, PET scans) identifies bone lesions.
Leukemia diagnosis often starts with a complete blood count (CBC) showing abnormal blood cell numbers. A peripheral blood smear identifies immature cells in the bloodstream. A bone marrow biopsy confirms the diagnosis, determines the type, and assesses disease extent.