Overview
A tenosynovial giant cell tumor (TGCT) is a soft tissue tumor. A TGCT starts as a growth of synovial cells in the synovium. The synovium is tissue that lines the joints and the structures around them. Those structures include bursae and tendon sheaths. Bursae are tiny fluid-filled cushions that protect joints. A joint is where two or more bones meet. A tendon connects bone to muscle. Tendon sheaths cover tendons and help them move smoothly.
There are two main types of TGCT.
Localized TGCT used to be called giant cell tumor of the tendon sheath (GCTTS). Localized TGCT is sometimes called nodular TGCT. It typically appears as a lump. It often affects the fingers and hand near tendon sheaths or finger joints.
Diffuse TGCT used to be called pigmented villonodular synovitis (PVNS). Diffuse TGCT can grow through several parts of a joint and into nearby tissues. It typically affects large joints in the knees, hips and ankles. It can grow into nearby tissue and damage a joint.
Both types are now grouped under the name tenosynovial giant cell tumor (TGCT). But you still may see GCTTS and PVNS in medical reports.
The two types look very similar under a microscope. But they typically grow and act differently. TGCTs are often benign, which means they are not cancer.
TGCTs most often affect adults in their 30s to 50s. These tumors are very rare in children, but they can happen at any age.
Types
The main types of TGCT are localized TGCT and diffuse TGCT. Localized TGCT also may be called nodular TGCT. Both types often are benign. The cells of these types look alike under a microscope. The types are often diagnosed by how the tumor grows and looks on imaging.
Localized TGCT. This type usually appears as one or more well-defined lumps in one area. This means it is less likely to spread through the joint lining. It often affects the fingers and hand near tendon sheaths or finger joints. It less commonly affects the foot, ankle or knee.
Diffuse TGCT. This type usually grows through many parts of a joint and into nearby tissue. It typically affects large joints in the knees, hips and ankles. It can involve several parts of a joint and extend into nearby soft tissues, tendons and muscles.
Malignant TGCT is a separate, extremely rare cancer that is different from localized and diffuse TGCTs.
Symptoms
Symptoms can vary by TGCT type and where the tumor is located.
Localized TGCT. This type, also called nodular TGCT, most often causes a firm lump that grows slowly. The lump often does not hurt. However, some people with localized TGCT may feel some pain and tenderness. If the lump or tumor is near a finger joint, it may be hard to bend and straighten the finger. If it presses on a nearby nerve, it may cause a tingling feeling.
Diffuse TGCT. The symptoms of diffuse TGCT may include:
- Swelling.
- Stiffness.
- Pain or tenderness.
- Reduced joint movement.
Diffuse TGCT can cause bleeding inside the joint. The bleeding may happen more than once.
Over time, diffuse TGCT can damage the joint's cartilage and nearby structures, including bones and tendons.
When to seek care
Make an appointment with a healthcare professional if you have symptoms that worry you or are not going away. These symptoms may include:
- A new, growing lump or tumor under the skin near a finger, wrist or ankle or around a joint.
- Joint pain, stiffness or swelling where the lump is growing.
- Trouble bending or straightening a finger.
If you have already been diagnosed with TGCT, call your healthcare team if your symptoms get worse or new symptoms develop.
Causes
The exact cause of localized and diffuse TGCTs is not known. Researchers have found gene changes in some TGCT tumors.
Risk factors
The exact risk factors for TGCT are not known. A TGCT can occur at any age. Risk may vary by age and sex at birth.
Age. TGCT can happen at any age. Localized TGCT is often more common in adults in their 30s to 50s. Diffuse TGCT usually affects younger people but can happen at any age. TGCT in children is extremely rare.
Sex at birth. Localized TGCT and diffuse TGCT are more common in women.