Medical terms A–Z

An inactive treatment or procedure that is intended to mimic as closely as possible a therapy in a clinical trial.

Refers to a clinical study in which the control patients receive a placebo.

The placenta forms in the uterus during pregnancy, exchanging oxygen, nutrients, and waste between a pregnant person and the developing fetus.

The transfer of blood from a placenta to an individual whose own blood production system is suppressed.

Timing decides whether it can work at all, because the drug acts on the release of an egg and not on anything afterward.

The active ingredient in cholesterol-lowering spreads, backed by a measurable drop in LDL but not by proof of fewer heart attacks.

One word, three unrelated meanings: a skin lesion, a fatty deposit inside an artery, and the bacterial film that coats teeth.

Plasma and serum are not interchangeable, since serum is what remains after blood clots and has given up its clotting proteins in the process.

A plasma cell is a mature immune cell derived from an activated B cell that manufactures large quantities of a specific antibody.

A type of cancer that begins in plasma cells (white blood cells that produce antibodies).

A growth of the antibody factories of the immune system, ranging from a harmless clone to widespread disease in the bones.

The outer membrane of a cell.

A type of immune cell that makes large amounts of a specific antibody.

Having to do with plasma cells (a type of white blood cells).

A single collection of abnormal antibody-making cells, which may stay solitary or prove to be the first sign of myeloma.

The process of separating certain cells from the plasma in the blood by a machine; only the cells are returned to the person.

A surgeon who specializes in reducing scarring or disfigurement that may occur as a result of accidents, birth defects, or treatment for diseases.

Grafts and flaps are the trade's basic tools, moving living tissue from a place where it can be spared.

Count and function are separate questions, so a bleeding problem can exist in someone whose platelet number looks entirely normal.

(Other name for: cisplatin)

(Other name for: cisplatin)

One element with two unrelated medical jobs: the core of a chemotherapy family, and a corrosion proof metal inside implanted devices.

It is a prodrug: the tablet does nothing until the liver converts it, and some people carry an enzyme variant that converts it poorly.

A drug used to reduce the amount of testosterone made in patients with advanced symptomatic prostate cancer for which no other treatment options are available.

Pleomorphic describes cells, tissue, or organisms that appear in varied shapes and sizes rather than in one uniform, consistent form.

A drug that works by cutting a tether, so stem cells released from the marrow can simply be drawn off through a vein.

The pleura is a two layered membrane enclosing each lung, producing a thin fluid film that lets the lungs glide smoothly against the chest wall.

The space enclosed by the pleura, which is a thin layer of tissue that covers the lungs and lines the interior wall of the chest cavity.

Fluid around the lung is a finding rather than a diagnosis, and analyzing a sample of it is what points toward the cause.

Stripping out a lining so the lung sticks to the chest wall, which is the aim: a space that can no longer refill.

Pain that arrives with the breath and stops when breathing stops is the signature, and it points at the lining rather than the lung.

Pleurodesis is a procedure that deliberately inflames the pleura to fuse its two layers together, preventing recurrent fluid buildup around the lung.

A rare and very aggressive (fast-growing) cancer that forms in tissues of the lung and pleura (a thin layer of tissue that covers the lungs and lines the interior wall of the chest cavity).

Plevitrexed is an investigational drug studied for its ability to block a cellular enzyme that dividing cancer cells need to copy DNA.

A nerve that has become thick and misshapen due to the abnormal growth of cells and tissues that cover the nerve.

A disorder affecting a network of nerves, blood vessels, or lymph vessels.

An antibiotic isolated from the bacterium Streptomyces plicatus with antineoplastic activity.

A cyclic depsipeptide isolated from the marine tunicate Aplidium albicans.

Named for the shape of a cell rather than its lineage, so the abbreviation has always covered two separate diseases at once.

The number of sets of chromosomes in a cell or an organism.

A disorder marked by anemia caused by iron deficiency, and a web-like growth of membranes in the throat that makes swallowing difficult.

Pluripotent describes a cell capable of developing into nearly any specialized cell type found in the body.

A cell that is able to develop into many different types of cells or tissues in the body.

A substance being studied in the treatment of cancer.

A monoclonal antibody that is being studied in the detection and treatment of cancer.

A synthetic tetrahydroisoquinoline alkaloid related to the marine natural compounds Jorumycin and the family of Renieramycins, obtained from molluscs and sponges, respectively, with potential…

A type of immune cell that has granules (small particles) with enzymes that are released during infections, allergic reactions, and asthma.

A substance that is being studied for its ability to protect against the gastrointestinal side effects caused by fluorouracil.

One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features.

A device that is used to help a person talk after a laryngectomy.

An polyvalent vaccine used to prevent infection by the bacterium Streptococcus pneumoniae.

Taking a whole lung leaves a space the body must fill, and that space is what separates the operation from smaller lung resections.

Bacteria, viruses, fungi, inhaled material and radiation can all produce pneumonia, so the name describes a pattern of lung injury rather than one illness.

Pneumonitis is inflammation of lung tissue from a noninfectious cause, distinct from pneumonia, which usually implies an infection.

Air in the wrong place: the lung does not burst, it simply loses the gentle suction that holds it open against the chest wall.

(Other name for: pneumococcal polyvalent vaccine)

A plasmid DNA cancer vaccine encoding the intracellular domain (ICD) of the HER-2/neu proto-oncogene.

Paroxysmal nocturnal hemoglobinuria.

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

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

(Other name for: pneumococcal polyvalent vaccine)

Feet carry the whole body's weight and sit furthest from the heart, which is why problems there often announce a condition elsewhere.

A type of enzyme involved in many functions of the cell, including the repair of DNA damage.

A substance that blocks an enzyme involved in many functions of the cell, including the repair of DNA damage.

A synthetic RNA that imitates a virus, used to rouse the immune system rather than to attack anything directly.

A stretch of synthetic double-stranded RNA carrying no message at all, built solely to look to the body like a virus.

A synthetic complex of carboxymethylcellulose, polyinosinic-polycytidylic acid, and poly-L-lysine double-stranded RNA.

An enzyme involved in many functions of the cell, including the repair of DNA damage.

A substance that is being studied in the treatment of cancer and for its ability to stimulate the immune system.

The soot chemicals made whenever something organic burns badly, and among the first substances ever shown to cause cancer.

A condition marked by infertility, enlarged ovaries, menstrual problems, high levels of male hormones, excess hair on the face and body, acne, and obesity.

The word vera, Latin for true, separates it from a rise in red cells that is merely a reaction to something else.

Polyethylene glycol is a synthetic polymer used in medications, ointments, and laxatives for its water holding and drug stabilizing properties.

(Other name for: therapeutic immune globulin)

A therapeutic formulation consisting of camptothecin, an alkaloid isolated from the Chinese tree Camptotheca acuminata, conjugated with polyglutamate.

A polymer is a large molecule built from many repeating units, a structural pattern shared by plastics, DNA, and proteins.

A common change in the genetic code in DNA.

Named for a nucleus that looks like several joined beads, these are the first white cells to reach an infection.

(Other name for: amoxicillin)

An inflammatory disease of the muscles closest to the center of the body.

An older label for damage affecting many nerves at once, kept mainly where inflammation is genuinely the cause.

A polyp is a growth that projects outward from the lining of a hollow organ, such as the colon, stomach, or nose.

A polypectomy removes a polyp, most often during an endoscopic procedure such as a colonoscopy, to treat or evaluate an abnormal growth.

A polypeptide is a chain of many amino acids joined together, the structural building block from which one or more folds into a functional protein.

A vast family of plant compounds behind bitterness, astringency and some plant colors, and among the most studied parts of the diet.

A substance being studied in the prevention of cancer.

(Other name for: kunecatechins ointment)

Polyposis is the development of numerous polyps, growths projecting from a mucous membrane, most often described within the colon.

A polysaccharide is a large carbohydrate built from many linked sugar units, a category that includes dietary starch, stored glycogen, and structural fibers.

A protein-bound polysaccharide derived from the mushroom Trametes versicolor (Turkey Tail) with immunoadjuvant and potential antitumor activities.

A polysomnogram, commonly called a sleep study, records brain activity, breathing, heart rhythm, and muscle activity overnight to help diagnose sleep disorders.

A fatty acid containing more than one double bond (C=C).

A cancer vaccine consisting of whole irradiated heterologous melanoma cells which express multiple melanoma-related antigens.

Pomalidomide is an approved oral treatment for multiple myeloma that alters immune activity and blood vessel formation around tumor cells.

Pomegranate is a fruit bearing shrub whose seeds and juice are eaten as food and studied for their antioxidant content.

A tart red juice studied mostly for its plant polyphenols, with laboratory findings that human trials have not matched.

A liquid extract preparation derived from pomegranate (Punica granatum) seeds with antioxidant, and potential antineoplastic and chemopreventive activities.

A pill formulation of polyphenol extracts derived from the fruit of the deciduous shrub Punica granatum with antioxidant and potential chemopreventive activities.

(Other name for: pomegranate-extract pill)

Damage to it produces combinations of findings so characteristic that the site can often be named before any scan is done.