Many of these medical terms may be used by your healthcare team when discussing your TGCT and treatment plan.
A Ablation:A medical procedure paired with surgery where heat or intense cold is used to destroy remaining tumor cells.
Anterior: Anterior is a medical term specifying a direction, generally the front side.
Arthroplasty: A surgical technique used to remove and replace damaged joints using metal, ceramic, or non-metal material. The goal of this surgery is to reconstruct or replace the joint.
Arthroscopy (Arthroscopic surgery): A surgical technique that utilizes multiple small incisions into which a camera and tube are inserted. The camera allows the surgeon to visualize inside the joint and project it on a monitor. The surgeon will use the other small incisions to insert surgical instruments to cut and remove damaged tissue and loose tumors. Both types of TGCT may be operable using this technique, Although depending on the size and extent of disease, this surgical technique may lead to incomplete removal.
B Baker's Cyst: A fluid-filled sac that forms in the back of the knee (popliteal fossa). Swelling from the knee pools into the back region of the knee which leads to an often visible lump, and may be painful. These are commonly associated with TGCT and degenerative joints. These are not specific to TGCT and can occur due to injury and other inflammatory processes.
Benign: A non-cancerous tumor. This tumor may be locally very aggressive but does not spread to other organs or joints and is not life-threatening.
Biopsy: A procedure used to remove a small tissue sample and analyze the cells under a microscope. This can either be performed with a needle or surgical procedure depending on the size and location of the tissue-of-interest.
Bursa (Bursae is plural): This is a fluid-filled sac lubricating the area between bone and soft tissue, bone and tendons, and bone and muscles/joints. The sac functions to reduce wear and tear.
C Cancer: Cancer is an umbrella term for diseases that have cells that are life-threatening and can invade and spread to healthy cells. TGCT is not cancerous, impacts a single joint, and is rarely life-threatening.
Cartilage: Firm and flexible connective tissue type that serves for structural support for the joints and bones, keeping bones from rubbing against one another. The knee has two different types of cartilage, articular and meniscus. Articular cartilage is a smooth tissue that covers the ends of bones. The meniscus is the cartilage between the bone, allowing shock absorption with wear and tear. Cartilage is not as flexible as tendons or ligaments.
Chronic: Diseases and symptoms described as chronic are persistent and long-lasting.
Clinical Trial: A research study that uses human participants to extend scientific knowledge. In the case of TGCT, there are observational studies where TGCT patients are just monitored to learn about the disease states. Another form of study is when TGCT patients are given a medicine and tracked for the impact of the medicine on the tumors and the potential side effects caused by that medicine.
Connective Tissue: This tissue type connects, separates, and supports all other types of tissue within our body.
Continuous Passive Motion (CPM) Machine: The CPM machine is a device used post-operatively to bend the joint, reducing swelling, pain, and stiffness. CPM increases range of motion. This device is commonly used after hip or knee surgery.
Colony stimulating factor 1 (CSF1): CSF1 is a protein used by cells to signal growth, survival, and development. TGCT over-produces this protein, leading to the recruitment of other cells to become part of the tumor.
Complete Response: Complete response refers to when a subject in a clinical trial has no measurable disease following a medication treatment via a measuring criteria such as RECIST.
Cryosynovectomy: A surgical technique during a synovectomy where a liquid nitrogen spray is used to make the joint uninhabitable by tumor cells. This is commonly used as an attempt to reduce recurrence, although it is inconclusive if it impacts recurrence rates. 1
Cyst: A cyst is a sac-like pocket of fluid, air, or other substances. Most cysts are benign. Cysts can develop almost anywhere.
D Debridement/debulking: Removal of part of the disease but not all of it. The benefit of this is controversial and a multidisciplinary team should be consulted.
Diffuse: A form of TGCT that grows in and around the joint, tendon sheath, or bursae and is known for its aggressive characteristics. These tumors tend to grow quite large, have no defined boundary, and grow in larger joints, such as, the knee (75% of diagnosed), the hip, and the shoulder. This subtype may infiltrate all or part of the joint. Subtype such as diffuse disease are the single risk factor for recurrence. For more information on the types of TGCT, go to Types of TGCT.
E Edema/Effusion: Swelling caused by excessive fluid (often synovial fluid) trapped in tissue. Endpoints:In clinical trials, an endpoint is an event or outcome that can be measured objectively to determine whether the intervention being studied is beneficial. Some clinical trials intend to demonstrate a medication is effective at shrinking tumors and therefore, tumor shrinkage would be the primary endpoint. Other clinical trials may intend to demonstrate that a medication is able to target a biological process (known as a pharmacodynamic study). In this example, the endpoint is demonstrating target engagement of the medication for the target. Clinical trials can have more than one endpoint but the main measurement of interest is known as the primary endpoint. Several secondary, tertiary, or exploratory endpoints can be included in the same trial to inform future trials.
Embolization: This treatment approach cuts off the blood supply to a tumor by inserting beads or coils into an artery.
F Fibroblasts: This is a type of connective tissue cell that produces collagen and acts as structural support throughout your body. These are the most common connective tissue cell type.
Foot Drop: This is a general term for a syndrome in which a patient has difficulty bending your foot at the ankle or flex your toes and/or ankle. This is a common post-operative complication seen with knee surgeries.
G Giant Cell Tumor of the Tendon Sheath (GCT-TS): GCT-TS is now a term used synonymously with localized TGCT.
H Hemosiderin Deposition: Hemosiderin is an iron-storage compound in your tissue, commonly present in the tumors creating an orange and brown stain. This does not change iron levels within your body. TGCT is typically pigmented due to hemosiderin leading to the original name of pigmented villonodular synovitis.
Hoffa's Fat Pad: A soft tissue pad that as a protective cushion separating the kneecap from the shin and thigh bone.
I Idiopathic: A disease which arises spontaneously and randomly with an unknown cause. TGCT is idiopathic.
Insidious: A term used to describe the disease or development of a symptom that is a gradual and/or has a slow onset of the disease.
J Joint: A location of connective tissue where two bones meet, linking the skeletal system and allowing different types of movement. Joint Preserving Treatment: A form of treatment that protects the joint, possibly delaying the need for a joint replacement. This can include surgeries like joint reconstruction, physical therapy, or nonsurgical options.
L Ligament: A short band of flexible and firm fibrous connective tissue that attaches one bone to another bone. This holds the bones together and provides stability.
Limb Salvaging Surgery: This phrase encompasses any surgical approach that attempts to remove a tumor in a limb without removing the limb. The bone and tissue surrounding the tumor may also be removed and replaced. These surgeries attempt to preserve the function and appearance of the limb.
Localized: A form of TGCT that grows inside and outside the joint, tendon sheath, or bursae. Localized TGCT tend to grow in smaller joints, such as fingers, toes, wrists, and knees. These tumors tend to be small and present with a clear boundary, sometimes encapsulated, making them easier to completely remove during surgery. This is also referred to as nodular TGCT. For more information on the types of TGCT, go to Types of TGCT.
N Neoplasm: A term, synonymous with tumor, used to describe a mass of cells that is either benign or malignant.
Neuropathy: A disease or symptom as a result of peripheral nerve damage, typically causing numbness and weakness in the affected limb. This can be a post-operative complication or a complication of advanced disease.
Nodule: A small mass of soft tissue that appears rounded. These small tumors can be loose in the joint or attached to the joint lining.
Non-Malignant (non-cancerous): Non-malignant means that the tumor cells are unable to invade and spread among health tissue. Non-malignant also can refer to benign.
M Magnetic Resonance Imaging (MRI): MRI is an imaging technique used to diagnosis TGCT. This technique is used in radiology to see soft tissue and other anatomy of the body. Using a strong magnetic field, radio waves, and magnetic gradients, an image can be generated that includes skeletal structures, vasculature, soft tissue, and organs. Contrasting dye, known as a gadolinium-based dye, can be used to enhance the imaging quality of soft tissue. This technique does not emit ionizing radiation, unlike X-rays and CT scans.
Malignant: Malignant is a term used to describe an abnormal tumor cell that invades and spreads among healthy tissue, also known as cancerous.
Medical Oncologist:Medical doctor specialize in diagnosing and treating tumors with medications, including other soft tissue tumors like TGCT. These doctors should be part of the multidisciplinary team approach. To find a Multidisciplinary team, check out our Specialists list.
Metastasis: Malignant, also known as cancerous, cells can spread from the primary tumor location to a secondary location, such as the lungs, liver, or other limbs. Metastasis is used as another word for cancerous spread. TGCT is a single joint disease and does not spread.
Monocytes: Monocytes are a type of white blood cells that aid in the immune response. These cells are one of the types of cells recruited from the TGCT cells to become part of the tumor.
Mononuclear: Mononuclear refers to a characteristic of a cell type. TGCT cells can be mononuclear or multinuclear. Mononuclear means that the cells have a single rounded center. Pathologists can determine the cell type based on features of the cell. White blood cells, such as monocytes, commonly have single rounded centers and are part of the tumor.
Morbidity: A general term for a physical or psychological illness or impairment. This is often used to describe chronic diseases that may lead to different illnesses with time.
Multinuclear: Multinuclear refers to cells with multiple rounded centers. This occurs when a TGCT cell fuses with a monocyte, a type of white blood cell. TGCT has different types of cells as part of its tumor and pathologists use these characteristics to diagnose patients.
O Objective Response Rate (ORR): ORR is defined as the percentage of patients that had a partial or complete response to a medication in a clinical trial. Partial responders have 30% or more shrinkage (and no new growth) and complete responders have no measurable disease determined by MRI following a treatment period. The ORR takes into account both partial and complete responders to give an overall response rate.
Oncologist:Medical doctor specialize in diagnosing and treating tumors with medications, including other soft tissue tumors like TGCT. These are frequently referred to as medical oncologists and should be part of the multidisciplinary team approach.
Open Surgery: A surgical technique that utilizes a large incision to gain access to a joint or bone. For more information on the Open Surgery, go to Surgery.
Osteoarthritis: Osteoarthritis is the most common form of arthritis. This occurs when the tissue at the end of and between bones wears down. This is different than rheumatoid arthritis which is an autoimmune disorder.
Orthopedic Oncologist: A medical doctor that has specialized training in surgery to treat tumors. Orthopedic oncologists should be consulted for the treatment of TGCT.
Orthopedic Surgeon:A medical doctor that specializes in operating on skeletal and anatomical structures. Generally, orthopedic surgeons fall into sports medicine, generalists, upper extremity, or lower extremity specializations. It is important to have a multi-disciplinary team that includes an orthopedic oncologist and medical oncologist that specializes in soft tissue and sarcomas instead of a provider that specializes in the anatomical area of interest.
P Partial Response: Partial response refers when a subject in a clinical trial has partial shrinkage following a medication treatment (30% or more) via a measuring criteria such as RECIST.
Posterior: Posterior is a medical term specifying a direction, generally the back side.
Prognosis: Prognosis refers to the expected outcome on the course of a disease. A healthcare provider makes an assessment on the prognosis based on the disease, patient history, and other patient specific characteristics, such as treatment, diagnosis, and symptoms.
Progression Free Survival (PFS): PFS refers to the duration of time during and after treatment of a disease until the disease progresses or gets worse. This is often used in clinical trials as a measurement for drug effectiveness.
Prosthesis: An artificial body part, typically describing the hardware used for a joint replacement.
Pigmented Villonodular Synovitis: A term that was used prior to the 2013 to describe diffuse TGCT.
R Radiation: A therapy that uses targets and kills cells using ionizing radiation. This can be done through local administration, Y-90 injections, during surgery or through external beam pre/post-operatively. The effectiveness of radiation on TGCT is questionable. There is a long-term risk of radiation-induced sarcoma, permanent irreversible joint damage, and lack of shown benefit deters its use. Consult with your healthcare team, if radiation has been suggested for you. For more information on radiation, go to Radiation.
Radiosynoviorthesis (Radiosynovectomy): A novel technique used during the removal of the synovial membrane to locally administer a small amount of beta-emitting atom to the synovium. This is a form of localized radiation therapy. This has not been found to reduce recurrence or improve outcomes and therefore, is not recommended.
Range of Motion (ROM): ROM refers to the mobility and flexibility of a joint. This can be measured as the distance and direction a joint can move to its full potential.
RECIST: is a standard way to measure the response of a tumor to a treatment determined by MRI for a clinical trial. In clinical trials, RECIST is used to determine who responds to a drug and to calculate an objective response rate (ORR). RECIST evaluation criteria takes measurements from the sum of the longest diameter of tumors and determines if a patient has a partial response (some shrinkage), complete response (undetectable disease on MRI), stable disease (no change), or progression (growth during treatment). This is considered a validated endpoint in trials but is imperfect for TGCT because TGCTs are 3-dimensional tumors where diameters may underestimate the treatment response. Therefore, volume-based measurements are also sometimes used to account for the 3-dimensional shape of TGCT.
Recurrence: Recurrence is the reappearance of a tumor following treatment. Diffuse TGCT has recurrence rates of around 50-70%, while localized TGCT has recurrence rates around 15%. Recurrence can also occur due to incomplete removal of the tumor during surgery. Recurrence is determined using a baseline and subsequent MRIs following a surgery. For more information on TGCT types and recurrence, go to Types of TGCT.
Recurrence Free Survival (RFS): RFS is the length of time after a primary treatment ends that the patient goes without recurrence of symptoms or disease. This is commonly measured during a clinical trial to evaluate how well a drug treatment may work.
Residual Disease: TGCT that is not completely removed during surgery is known as residual disease. Symptoms may relapse due to residual disease or due to recurrence.
Rheumatologist: A Rheumatologist is a medical doctor that has had extra training and experience in the diagnosis of arthritis and other musculoskeletal diseases.
S Sarcoma: A general term for a cancerous soft tissue tumor that is made up of connective tissues, such as cartilage, bone, fat, vascular, and other tissues. TGCT is not a cancer, however, sarcoma specialists are an important part of a healthcare team since they have experience in soft tissue tumors similar to TGCT.
Soft Tissue Tumor: An umbrella term for all benign and malignant tissues made out of connective tissue, such as cartilage, bone, synovial tissue, fat, vascular tissue, smooth muscles, and other tissue.
Stable Disease: A term used to describe a tumor that is neither growing nor shrinking. Stable disease may include the presentation of symptoms or it may not.
Standard of Care: Standard of care refers to the recommended treatment for a disease. Different patients may require different standards of care based on their specific disease. TGCT does not have a consensus on the standard of care, making treatment more patient-specific and physician-specific.
Subtype: TGCT has 2 subtypes, diffuse and localized (sometimes called nodular). This allows a subdivision of a disease into smaller categories based on disease features and presentation. For more information on TGCT types, go to Types of TGCT.
Synovium: Soft tissue that lines the cavity of the synovial joint, tendon sheath, and bursae. The synovium lines the inner surface of the joint.
Synovial Fluid: Synovial fluid is a viscous fluid found in the cavity of the synovial joint. This fluid lubricates the joint and allows movement to occur with ease.
Synovectomy: A surgical procedure where the synovial tissue lining of the joint is removed.
T Tendon: A fibrous connective tissue that serves to move the bone by attaching muscle to bone.
Tendon sheath: A layer of the synovial membrane around a tendon. This helps the tendon to stretch and not get stuck.
Tenosynovial: A term referring to the tendon sheath and synovium.
TGCT: A type of non-cancerous, locally aggressive, rare tumor disease occurring in and surrounding the joint, tendon sheath, and/or the bursae. There are two subtypes: diffuse and localized. For more information on TGCT, go to About TGCT.
Tumor: An abnormal growth of cells that create a solid mass. Tumors can be benign or malignant.
Y Yttirum-90 Radiotherapy (Y-90): A locally administered radiation therapy that uses a radioactive isotope to kill cells.
