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anti-inflammatory medications

Drugs or substances that reduce inflammation (redness, swelling, and pain) in the body. Anti-inflammatory agents block some molecules in the body that cause inflammation. They also are used to treat a variety of conditions.


A surgical procedure performed to restore the function of a joint. An artificial joint (called a prosthesis) may be used.

arthroscopic surgery (pronounced AR-thruh-SKAW-pick)

A medical procedure where a narrow tube and camera are inserted through a small cut (incision) in the skin. Through the cut, surgeons see inside the area on a video monitor. To remove a tumor, the surgeons use thin surgical tools that are inserted through other small cuts.

Arthroscopic surgery can be used to treat both localized and diffuse TGCT. But it can be difficult for removing diffuse tumors; they are often very large and irregular in shape, and their borders are not easy to see (in surgery).

For more information on how arthroscopic surgery is used to treat TGCT, see TGCT treatment.


benign (pronounced bee-NINE)

Not cancerous. Tumors that are benign may grow larger, but they do not spread to other parts of the body.


The removal of a small sample of tissue from the body, which is then examined. A biopsy helps to establish an accurate diagnosis.


A sac filled with fluid found in the joints of the synovium (thin layer of tissue that lines the joints). It helps reduce rubbing (friction) between bones and tendons.



Describes a condition or disease that persists over a long period of time. People may have chronic diseases or symptoms.

connective tissue

A type of tissue that connects, supports, and gives structure to other tissues and organs.


Colony-stimulating factor 1 (CSF-1), a protein involved in the growth of certain cells. In TGCT, researchers believe that too much CSF-1 in some cells lining a joint may attract other cells. These other cells merge and form a tumor.


degenerative joint disease

A disease in which the cartilage in joints breaks down. It is also called osteoarthritis.

diffuse TGCT

A type of TGCT that grows in and around a joint and its surrounding area. Diffuse tumors are usually found in large joints like the knees, shoulders, and hips. Diffuse tumors are usually larger than 5 centimeters (larger than 2 inches); an AA battery is about 5 centimeters (or about 2 inches) long. The borders of the tumors are not easy to see (in surgery).



Giant cell tumor of the tendon sheath. A term sometimes used for “localized TGCT.”


joint, joints

A location in the body where 2 or more bones meet. A joint usually helps with motion.

joint replacement, joint arthroplasty

Surgery that rebuilds and replaces some or all of a damaged joint with artificial parts. The parts are made of metal or other materials. Total-joint arthroplasty may be used to treat severe cases of diffuse TGCT.



Bands of tough tissue around joints. The bands connect bone to bone, support joints, and limit joint movement.

localized TGCT

A type of TGCT that grows outside of or within a joint. Localized tumors are usually found in small joints like fingers, toes, wrists, or ankles. Tumors are usually small, and their borders are easy to see (in surgery).



Cancerous. Malignant cancer cells can invade and spread to other parts of the body.

meniscal tear

A tear in the meniscus. It may occur by suddenly twisting the knee while bearing weight on it. It is one of the most common
knee injuries.


A C-shaped piece of cartilage. It acts as a cushion between the shinbone and thighbone.


MRI stands for magnetic resonance imaging. It is a test that uses powerful magnets and radio waves to produce detailed pictures of the inside of the body.


nodule (pronounced NAW-jewl)

A small mass of tissue that appears as a rounded lump or knot.


Not cancerous.

nurse practitioner

A nurse with a graduate degree in advanced nursing. Nurse practitioners work in a variety of specialties and provide a broad range of services in healthcare.



A doctor who diagnoses and treats tumors.

open surgery

A traditional type of surgery. Surgeons use a blade (scalpel) to make a cut in the skin. The cut is large enough for them to see and reach the part of the body to be treated.

For more information on how open surgery is used to treat TGCT, go to TGCT treatment.

orthopedic surgeon

A surgeon who diagnoses and treats disorders of the bones, joints, ligaments, tendons, and muscles.


The most common form of arthritis. It occurs when the cartilage that protects and cushions the ends of bones wears down, usually over time. Osteoarthritis can damage any joint, but it commonly affects the hands, knees, hips, and spine.



Pathologists are doctors who evaluate samples of tissues or bodily fluids. They check for the presence of certain substances.

physical therapist

A trained expert who helps people with strength, mobility, and fitness.

primary care physician (PCP)

A medical doctor who is often the first doctor people visit when symptoms occur. This doctor can assess symptoms, review medical history, and order routine tests as needed. When necessary, a primary care physician may provide referrals to specialists.


The expected course of a disease; a “forecast.” To make a prognosis, healthcare providers consider the disease and other factors, such as treatment history, diagnosis, and symptoms.


Pigmented villonodular synovitis. A term sometimes used for “diffuse TGCT.”



A doctor who uses X-rays, MRIs, and other medical imaging to help diagnose and sometimes treat diseases.

range of motion

The measure of the amount of movement possible in a joint. It is measured in degrees of a circle.

recur, recurrence, recurrent

The return of a tumor after treatment (which can include surgery); some tumors regrow. In TGCT, a tumor can recur or return—especially in diffuse TGCT—if the original tumor was not removed completely.

rehabilitation specialist

A trained expert who helps people recover from serious injuries or diseases.


A doctor who diagnoses and treats conditions that affect the joints, tendons, ligaments, bones, and muscles. Some of these conditions may include arthritis and other autoimmune diseases. In autoimmune diseases, your own immune system attacks your body by mistake.


sarcoma, soft tissue sarcoma

A general term for malignant tumors that start in cells of bones or connective tissues (like muscle and fat). Sarcoma specialists work with tumors that affect the joints; for that reason, they can be an important part of the team treating TGCT.

standard of care

The recommended approach to treatment for a condition or disease. The approach may vary for patients based on their
specific diagnosis.

steroidal drug

A medicine that is similar to hormones that the body makes to fight stress from illnesses and injuries. It is used to treat a variety of conditions, including to reduce inflammation.

synovial joint (pronounced sin-OH-vee-ul)

A type of joint; bones of the joint are surrounded by layers of tissue that lubricate the joint.

synovium (pronounced sin-OH-vee-um)

A layer of tissue that lines the joints.


tendon, tendons

A tissue that attaches muscle to bone. It is made up of fibers.

tendon sheath

A layer of synovial membrane; it surrounds and encloses a tendon. The sheath allows the tendon to stretch without
causing damage.

tenosynovial (pronounced TEN-oh-sin-OH-vee-ul)

Of or pertaining to the tendon sheath.


Tenosynovial giant cell tumor (TGCT) is a typically benign (not cancerous) tumor that occurs in or around a joint. It can reduce function and cause damage to nearby tissues. TGCT is known by two types: localized or diffuse. TGCT is also known as giant cell tumor of the tendon sheath (GCT-TS) or pigmented villonodular synovitis (PVNS). The World Health Organization uses TGCT as the overall term for these rare tumors.

tumor, tumors

An abnormal growth of cells that forms a mass.