Brain Tumor Glossary of Terms

Easily explore the meaning of hundreds of medical terms or words, many directly used in brain tumor-related terminology.

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Laboratory Study

Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.

Laboratory Test

A medical procedure that involves testing a sample of blood, urine, or other substance from the body. Tests can help determine a diagnosis, plan treatment, check to see if treatment is working, or monitor the disease over time.

Laser

A device that forms light into intense, narrow beams that may be used to cut or destroy tissue, such as cancer tissue. It may also be used to reduce lymphedema (swelling caused by a buildup of lymph fluid in tissue) after breast cancer surgery. Lasers are used in microsurgery, photodynamic therapy, and many other procedures to diagnose and treat disease.

Laser Surgery

A surgical procedure that uses the cutting power of a laser beam to make bloodless cuts in tissue or to remove a surface lesion such as a tumor.

Laser Therapy

Treatment that uses intense, narrow beams of light to cut and destroy tissue, such as cancer tissue. Laser therapy may also be used to reduce lymphedema (swelling caused by a buildup of lymph fluid in tissue) after breast cancer surgery.

Leptomeningeal Cancer

Cancer that has spread from the original (primary) tumor to the meninges (thin layers of tissue that cover and protect the brain and spinal cord). The cancer causes inflammation of the meninges. Also called carcinomatous meningitis, leptomeningeal carcinoma, leptomeningeal metastasis, meningeal carcinomatosis, meningeal metastasis, and neoplastic meningitis.

Lesion

An area of abnormal tissue. A lesion may be benign (not cancer) or malignant (cancer).

Limbic system

A group of subcortical structures (as the hypothalamus, the hippocampus, and the amygdala) of the brain that are concerned especially with emotion and motivation.

Lipoma brain tumor

Lipomas are benign fatty growths that can be found virtually anywhere in the body. They generally do not change much in size over time. If they are not causing a problem they will usually be left alone. A lipoma specifically in the brain may or may not be a problem. If in the corpus callosum, depending on size and location, it could conceivably cause hydrocephalus. Furthermore, if large, it could cause a deficit simply via mass effect. An MRI would be instrumental for evaluating this type of condition. Lipomas do not necessarily need to be treated. Only when they cause problems referable to their size and location do lipomas require intervention.

Liver Function Test

A blood test to measure the blood levels of certain substances released by the liver. A high or low level of certain substances can be a sign of liver disease.

Lobe

A portion of an organ, such as the liver, lung, breast, thyroid, or brain.

Lobectomy

Surgery to remove a whole lobe (section) of an organ (such as the lungs, liver, brain, or thyroid gland).

Low-grade

A term used to describe cells that look nearly normal under a microscope. These cells are less likely to grow and spread more quickly than cells in high-grade cancer or in growths that may become cancer.

Lumbar puncture

A procedure in which a thin needle called a spinal needle is put into the lower part of the spinal column to collect cerebrospinal fluid or to give drugs. Also called spinal tap.

Lysis

In biology, lysis refers to the breakdown of a cell caused by damage to its plasma (outer) membrane. It can be caused by chemical or physical means (for example, strong detergents or high-energy sound waves) or by infection with a strain virus that can lyse cells.