Myeloma Cancer: Pathology of the Disease

Multiple myeloma is a type of bone marrow cancer that affects the production of mature blood cells and weakens immune function. Multiple myeloma can affect any bones in which the bone marrow is active including the hips, pelvis, ribs, shoulders, skull and spine.

Myeloma Cancer Pathology

When the DNA of a plasma cell is damaged, the cell becomes abnormal. Abnormal plasma cells are called myeloma cells. An abnormal myeloma cell begins to divide rapidly, making many thousands of copies of itself.

Abnormal cells don’t develop, mature and die the way that normal cells do. Instead, they begin to accumulate into a mass of tissue called a tumor. After a while, myeloma cells will suppress the amount of normal blood cells in the bone marrow.

M Proteins in Multiple Myeloma

In healthy bone marrow, white blood cells mature into plasma cells, and each plasma cell makes a specific antibody to combat a specific antigen. However, myeloma cells produce only one type of antibody, called the monoclonal protein, or M protein.

As myeloma cells reproduce and spread, fewer and fewer healthy plasma cells are available to produce the variety of antibodies needed to fight off all the different antigens. This increases the risk of infection.

The five classifications of antibodies, also called immunoglobulins, are A, G, M, D and E. Although myeloma antibodies are called M proteins, not everyone with multiple myeloma overproduces immunoglobulin M (IgM). Multiple myeloma can involve an overproduction of any of the five antibody groups. An overproduction of IgG is the most common and an overproduction of IgE is the least common.

Multiplying Myeloma Cancer Pathology

When a myeloma tumor becomes large enough, it can extend beyond the bone marrow and damage the solid, outer part of the bone and the surrounding tissue. In most cases, myeloma cells circulate throughout the body via the bloodstream and form tumors in bone marrow in multiple parts of the body. This is why the disease is called multiple myeloma. M proteins can travel through the bloodstream and affect other organs, particularly the kidneys.

Types of Multiple Myeloma

Multiple myeloma is classified according to myeloma cancer pathology, as well as the presence and severity of myeloma symptoms, into these types:

• Asymptomatic myeloma is not considered an active form of the disease because the individual doesn’t experience any myeloma symptoms.
• Plasmacytoma involves a single myeloma tumor. People with plasmacytoma often develop multiple myeloma later in life.
• Symptomatic or active myeloma is characterized by the presence of M proteins in the blood or urine. Symptomatic myeloma is further classified according to the severity of myeloma symptoms into Stages I, II and III.
• Light chain myeloma or Bence Jones myeloma involves the production of incomplete immunoglobulins. These show up in the urine, but not in the blood. According to Myeloma Canada (2010), approximately 20 percent of people with multiple myeloma have light chain myeloma.
• Nonsecretory myeloma is the most challenging type to diagnose because M proteins don’t show up in either the blood or urine. This is a very rare type of bone marrow cancer.

Resources

Mayo Foundation for Medical Education and Research. (2009). Multiple myeloma: Causes. Retrieved September 24, 2010, from http://www.mayoclinic.com/health/multiple-myeloma/DS00415/DSECTION=causes

Myeloma Canada. (2010). Types of myeloma. Retrieved September 27, 2010, from http://www.myelomacanada.ca/en/typesofmyeloma.htm

Myeloma Institute for Research and Therapy. (n.d.). Basic pathology concepts of multiple myeloma. Retrieved September 24, 2010, from http://myeloma.uams.edu/about-myeloma/pathology.asp

National Cancer Institute. (2008). What is multiple myeloma? Retrieved September 23, 2010, from http://www.cancer.gov/cancertopics/wyntk/myeloma/page2

Seattle Cancer Care Alliance. (n.d.). Multiple myeloma facts. Retrieved September 24, 2010, from http://www.seattlecca.org/diseases/multiple-myeloma-facts.cfm

The Cancer Council NSW. (n.d.). Understanding multiple myeloma: Multiple myeloma explained. Retrieved September 24, 2010, from http://www.cancercouncil.com.au/editorial.asp?pageid=1105