Medical terms A–Z

This dome shaped skin growth appears within weeks and often resolves untreated, yet it can be nearly indistinguishable from squamous cell carcinoma.

A drug used to cause a loss of feeling and awareness and to induce sleep in patients having surgery.

Their presence alone says little; what matters is whether the body chose to make them or was driven to it by missing insulin.

One of a pair of organs in the abdomen.

Kidney cancer includes renal cell carcinoma in adults and Wilms tumor in young children, arising from different structures within the kidney.

A condition in which the kidneys stop working and are not able to remove waste and extra water from the blood or keep body chemicals in balance.

A test in which blood or urine samples are checked for the amounts of certain substances released by the kidneys.

Pain comes from the blocked tube stretching above the stone rather than from the stone scraping its way along.

The immune system's targeted assassin, destroying one marked cell at a time while leaving its healthy neighbors untouched.

A kilogram is the standard metric unit of body weight in medicine, central to accurate weight based drug dosing calculations.

A substance that is used to treat rheumatoid arthritis, and is being studied in the treatment of cancer.

A kinase is an enzyme that adds a phosphate group to another molecule, a reaction central to cell signaling, metabolism, and growth.

A substance that causes blood stem cells (cells from which other types of cells develop) to change into different types of blood cells and increases the number and actions of these cells in the blood.

A tumor whose whole difficulty is its address: small, slow to declare itself, and sitting where the liver's plumbing converges.

A bacterium that frequently causes lung, urinary tract, intestinal, and wound infections.

A substance taken from a marine organism that may be linked to a specific antigen to boost the immune response to that antigen.

Among the commonest chromosome differences in people, and among the most often missed, because the outward signs are easy to overlook.

A substance being studied in the treatment of cancer.

An inherited disorder in which there is a lower-than-normal number of neutrophils (a type of white blood cell that is important in fighting infections).

An inherited disorder in which there is a lower-than-normal number of neutrophils (a type of white blood cell that is important in fighting infections).

An inherited disorder in which there is a lower-than-normal number of neutrophils (a type of white blood cell that is important in fighting infections).

A gene that may cause cancer when it is mutated (changed).

A kretek is a clove-flavored cigarette that combines tobacco with ground cloves and other additives during manufacturing.

A drug being studied in the treatment of cancer.

Cancer found in the ovary that started in the stomach, and a sign the original disease has already traveled.

A type of herpesvirus that may cause Kaposi sarcoma (a rare cancer that can cause skin lesions) and a type of lymphoma (cancer that begins in the lymph system), especially in patients who have a…

A semisynthetic anticancer drug that is a type of antitumor antibiotic.

A substance being studied in the treatment of cancer.

An anticancer drug that belongs to the family of drugs called enzyme inhibitors.

L-arginine is an amino acid the body uses to build protein and to produce nitric oxide, a molecule that widens blood vessels.

A bacterial enzyme pressed into service as a drug, exploiting one thing leukemia cells cannot do that healthy cells can.

Made in the body and eaten in meat, it is the ferry without which long chain fats never reach the furnaces inside a cell.

One of twenty amino acids (molecules that join together to form proteins).

A drug being studied in the treatment of young adults with bone cancer that has gotten worse or come back.

A form of the hormone progesterone that is made in the laboratory and used to prevent pregnancy.

A substance that is being studied in the treatment of cancer.

Shrinking a laboratory onto a slide changes the physics as much as the scale, and that is rather the point of it.

The inner lining of the lips.

Research done in a laboratory.

A reference range shows what is usual in a healthy population, not what suits one person, so a flagged result is not automatically abnormal.

A gland that secretes tears.

Losing it after childhood is the normal human pattern; keeping it into adulthood is the genetic exception that spread with dairy farming.

Lactate dehydrogenase is an enzyme active in nearly all body tissues, and its blood level rises with cell injury from a wide range of causes.

Lactic acid is produced naturally in muscle and other tissue during energy metabolism and is also formed by bacteria that ferment food and skin products.

Lactic acid dehydrogenase is an enzyme found throughout body tissue, and a rising blood level points to cell damage from many causes, not only cancer.

Lactobacillus is a genus of bacteria that produces lactic acid and normally lives harmlessly in the human gut, mouth, and vaginal tract.

Lactoferrin is an iron binding protein in milk and other secretions that helps limit bacterial growth as part of innate immune defense.

Lactose is the natural sugar in milk that requires the enzyme lactase to be broken down and absorbed in the intestine.

Lactose intolerance results from insufficient lactase enzyme, leading to digestive symptoms after consuming milk or other dairy products.

A white blood cell that is stimulated in a laboratory to kill tumor cells.

A type of connective tissue found under the thin layer of tissues covering a mucous membrane.

Long filed as an odd inflammatory reaction, it is now recognized as a clonal growth driven by a mutation in one signaling route.

Wax recovered from sheep wool and purified, valued because it holds water against the skin much as the skin's own oils do.

A once-daily background insulin engineered to form a slow-release deposit under the skin instead of acting all at once.

It is the eye of keyhole surgery: instruments enter through separate ports, and the whole team operates from one magnified screen image.

Surgery to remove all or part of the prostate with the aid of a laparoscope.

Laparoscopic surgery uses small incisions, a camera, and long instruments to operate inside the abdomen or pelvis without the large opening open surgery requires.

Surgery done with the aid of a laparoscope to remove all or part of the colon through several small incisions made in the wall of the abdomen.

Surgery done with the aid of a laparoscope.

Trading one long wound for several small ones changes the recovery far more than it changes the operation performed inside.

A laparotomy is an open surgical incision through the abdominal wall, performed to directly examine, diagnose, or treat conditions inside the abdominal cavity.

A drug used with another anticancer drug to treat breast cancer that is HER2 positive and has advanced or metastasized (spread to other parts of the body) after treatment with other drugs.

A plant whose seeds and root have been used in some cultures to treat certain medical problems.

Lung cancer in which the cells are large and look abnormal when viewed under a microscope.

A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells.

Little food value is left by this stage; the work here is reclaiming water and packing what remains into stool.

Laryngeal structures and conditions involve the larynx, the part of the throat responsible for voice production and protecting the airway during swallowing.

Laryngeal cancer forms in the larynx, the structure used for breathing, swallowing, and speech, and most often begins in its lining cells.

A laryngectomee is a person who has undergone complete surgical removal of the larynx and now breathes through a neck opening.

A laryngectomy is a surgical procedure that removes all or part of the larynx, most often to treat laryngeal cancer.

Laryngitis causes hoarseness or voice loss when the vocal folds swell, most often from a viral infection, overuse, or irritant exposure.

A laryngoscope is a lighted instrument used to view the larynx, most often to guide placement of a breathing tube.

Laryngoscopy is a procedure to directly view the larynx, either with a hand held mirror or with a lighted instrument called a laryngoscope.

Known as the voice box, though its first duty is closing the airway, and speech is the ability that was added later.

Ordinary light spreads out and contains every color; a laser beam holds one wavelength and stays narrow, which is what makes it a tool.

The use of a low-level laser beam instead of an acupuncture needle to stimulate an acupuncture point.

Laser surgery uses a focused, high energy beam of light to cut, seal, or remove tissue with precision across many surgical fields.

Laser therapy applies a focused beam of light to cut, seal, or reshape tissue, with uses spanning surgery, eye care, dermatology, and supportive cancer care.

A feeling of tiredness, weakness, and lack of interest in daily activities.

Side effects of cancer treatment that appear months or years after treatment has ended.

A term used to describe cancer that is far along in its growth, and has spread to the lymph nodes or other places in the body.

Present but not announcing itself, a state that separates carrying something from being ill with it.

Lavender is an aromatic flowering plant whose oil is widely used in aromatherapy and traditional preparations for its calming scent.

A laxative is a substance used to promote bowel movements or ease the passage of stool, available in several different forms and mechanisms.

A drug being studied in the treatment of cancer.

Abnormal cells filling the milk-producing lobules, treated as a warning sign for both breasts rather than as a cancer of one.

LDH is the abbreviation for lactate dehydrogenase, an enzyme present in most body tissues whose blood level rises whenever cells are damaged or dying.

A complex molecule that has both protein and sugars.

Treatment with drugs that become active and may kill cancer cells when exposed to light.

A technique that uses electric current passed through a thin wire loop to remove abnormal tissue.

A source of free legal help for people who cannot pay, increasingly based inside clinics because so many health problems have legal roots.

A benign smooth muscle tumor, usually in the uterus or gastrointestinal tract.

Leiomyosarcoma is a rare malignant tumor arising from smooth muscle cells, most often found in the uterus, abdomen, or retroperitoneum.

A lemon is a citrus fruit valued as a natural source of vitamin C, historically important for preventing the vitamin C deficiency scurvy.

Most of the eye's focusing power comes from the cornea; the lens supplies the adjustable part, and that adjustment is what age removes.

A beta-glucan (a type of polysaccharide) from the mushroom Lentinus edodes (shiitake mushroom).

A form of the anticancer drug paclitaxel that is contained in very tiny, fat-like particles.

An adjective that quietly narrows the field to two of the three coverings, the pair the spinal fluid actually runs between.

Cancer that stops behaving like a lump and starts behaving like a fluid, settling wherever spinal fluid happens to flow.

A serious problem that may occur in cancer in which cancer cells spread from the original (primary) tumor to the meninges (thin layers of tissue that cover and protect the brain and spinal cord).