Glossary of Medical Terms

A common virus that remains dormant in most people. It causes infectious mononucleosis and has been associated with certain cancers, including Burkitt lymphoma, immunoblastic lymphoma, and nasopharyngeal carcinoma. Also called Epstein-Barr virus.

A small bruise caused by blood leaking from broken blood vessels into the tissues of the skin or mucous membranes.

A type of simple sweat gland that is found in almost all regions of the skin. These glands produce sweat that reaches the surface of the skin by way of coiled ducts (tubes). The body is cooled as sweat evaporates from the skin.

A very rare disorder in which too many histiocytes (a type of white blood cell) build up in certain tissues and organs and damage them. ECD most often affects the long bones of the arms and legs, but it can also affect the skin, lungs, heart, kidneys, brain, tissue behind the eyes, and the retroperitoneum (the back wall of the abdomen). The symptoms can range from mild to severe and life-threatening. ECD is most common in adults. It is a type of histiocytosis. Also called Erdheim-Chester disease.

A line graph that shows changes in the electrical activity of the heart over time. It is made by an instrument called an electrocardiograph. The graph can show that there are abnormal conditions, such as blocked arteries, changes in electrolytes (particles with electrical charges), and changes in the way electrical currents pass through the heart tissue. Also called EKG and electrocardiogram.

An herb native to North America that has been used to prevent and treat the common cold and other respiratory infections. Echinacea may interfere with treatment that uses the immune system to fight cancer. The scientific names are Echinacea purpurea and Echinacea angustifolia. Also called purple coneflower.

A computer picture of the heart created by bouncing high-energy sound waves (ultrasound) off internal tissues or organs of the chest. Echocardiograms show the size, shape, and position of the heart. They also show the parts inside the heart, such as the valves, and the motion of the heart while it is beating. An echocardiogram may be used to help diagnose heart problems, such as abnormal heart valves and heart rhythms, damage to the heart muscle from a heart attack, and heart murmurs. Echocardiograms can also show an infection on or around the heart valves, blood clots or tumors inside the heart, and fluid buildup in the sac around the heart.

A procedure that uses high-energy sound waves (ultrasound) to look at tissues and organs inside the chest. Echoes from the sound waves form a picture of the size, shape, and position of the heart on a computer screen (echocardiogram). The pictures can also show the parts of the inside of the heart, such as the valves, and the motion of the heart while it is beating. Echocardiography may be used to help diagnose heart problems, such as abnormal heart valves and heart rhythms, heart murmurs, and damage to the heart muscle from a heart attack. It may also be used to check for an infection on or around the heart valves, blood clots or tumors inside the heart, and fluid buildup in the sac around the heart.

A large network of proteins and other molecules that surround, support, and give structure to cells and tissues in the body. The ECM helps cells attach to, and communicate with, nearby cells, and plays an important role in cell growth, cell movement, and other cell functions. The ECM is also involved in repairing damaged tissue. Abnormal changes in the ECM may lead to the development of certain diseases, such as cancer. The ECM of cancer cells can affect how they grow and spread. Also called extracellular matrix.

A study that compares large groups of people instead of individuals for differences in things such as cancer rates. The groups can differ by location (for example, city, county, or country). They can also differ by time (a few days, years, or decades). Groups can be immigrants (compared with people who are native to the country) or people with different types of jobs. The Surveillance, Epidemiology, and End Results (SEER) Program conducts ecologic studies to collect information on cancer rates over time in certain parts of the United States. Also called ecological study.