What is Multiple Myeloma?

Multiple myeloma, also known as myeloma, is the second most common blood cancer. Multiple Myeloma starts in the plasma cells in bone marrow. The bone marrow is the soft, spongy tissue found in the center of many bones where blood cells are produced.

When the plasma cells become malignant, they create a defective protein that can grow out of control and crowd out the normal cells that help fight infection and disease. When the bad protein cells move into bone, they cause tumors. If the malignant cells form a tumor, it is called myeloma.

Healthy bone marrow and myeloma bone marrow comparison

In healthy bone marrow, B-cells, a type of white blood cell, develop into antibody-producing plasma cells when foreign substances (antigens) enter the body. In multiple myeloma, DNA damage to a B-cell transforms the normal plasma cell into a multiple myeloma cell. The cancerous cell multiplies, leaving less space for normal blood cells in the bone marrow, and produces large quantities of M protein.

In addition, groups of myeloma cells cause other cells in the bone marrow to remove the solid part of the bone and cause osteolytic lesions, or soft spots in the bone, resulting in weakened bones and increasing the risk of fractures. Although common, these lesions or other signs of bone loss do not occur in all patients with multiple myeloma.


Learn more about Multiple Myeloma

Symptoms of Multiple Myeloma
Causes of Multiple Myeloma
Diagnosis of Multiple Myeloma
Complications of Multiple Myeloma
Prognosis of Multiple Myeloma
Multiple Myeloma Treatment Options

Source: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer: Principles and Practice of Oncology. 5th ed. 1997:2350. Adapted with permission from Lippincott Williams & Wilkins.