You went to your doctor because of a joint problem and found out that you have tenosynovial giant cell tumor (TGCT). The term might be new to you, and hearing it may have caught you off guard.

When you’re given a diagnosis, you want to learn as much as you can about the disease and how it could affect your life. During your next doctor visit, you’ll want to ask more specific questions about your symptoms.

Here are nine questions to help you understand your symptoms and what they mean for your treatment.

TGCT isn’t the only disease that causes swelling, pain, and stiffness in the joints. Arthritis can produce these symptoms, too. And untreated TGCT can lead to arthritis over time.

Imaging tests can help your doctor tell the difference. In arthritis, your doctor will see narrowing in the joint space on an X-ray. The same test will show bone and cartilage damage in the joint with TGCT.

Magnetic resonance imaging (MRI) is an even more precise way to distinguish between the two conditions. An MRI will show changes to the joint unique to TGCT.

If you’ve been diagnosed with TGCT, but you’re not convinced that’s what you have, see another doctor for a second opinion.

The swelling is from inflammatory cells clustering together in the lining of your joint, or synovium. As the cells multiply, they form growths called tumors.

TGCT will typically grow, but some types grow faster than others. Pigmented villonodular synovitis (PVNS) can be localized or diffuse. The localized form responds well to treatment. However, the diffuse form can grow quickly and be difficult to treat.

Giant cell tumor of the tendon sheath (GCTTS) is a localized form of the disease. It usually grows very slowly.

They could. Most people start with swelling. As the tumor grows, it presses on nearby structures, which can also produce pain, stiffness, and other symptoms.

TGCT isn’t one disease, but a group of related conditions. Each type has its own set of symptoms.

If your knee or hip is swollen, you could have PVNS. This type can also affect joints like the shoulder, elbow, or ankle.

Growths in smaller joints like your hands and feet are more likely to be from GCTTS. Often you won’t have any pain with the swelling.

Not likely. TGCT isn’t cancer, so the tumors typically don’t grow beyond the joint where they started. Only rarely does this condition turn into cancer.

Some forms of TGCT grow faster than others. PVNS can grow quickly and damage the cartilage and bone around it, leading to arthritis. It can leave your joint permanently disabled if you don’t receive treatment.

GCTTS grows more slowly, and it’s less likely to damage your joints. After a careful discussion with your doctor, you may be able to wait to treat it if the symptoms don’t bother you.

The main treatment for TGCT is surgery to remove the tumor and damaged part of the synovium in the joint. Surgery can be done through one open incision (open surgery) or several small incisions (arthroscopy). If a joint is badly damaged, it may need to be replaced entirely.

Holding an ice pack to the joint may help with pain and inflammation. An over-the-counter (OTC) nonsteroidal anti-inflammatory drug (NSAID) like ibuprofen (Advil, Motrin) or naproxen (Aleve) can also help with pain and swelling.

To take pressure off a sore joint, rest it. Use crutches or another aid when you do have to walk.

Exercise is also important to prevent the joint from stiffening up or weakening. Ask your doctor whether a physical therapy program might be right for you.

Getting diagnosed with a rare disease like TGCT can feel overwhelming. You may need some time to process everything your doctor has told you.

You’ll feel more confident if you understand TGCT. Read up on the condition, and ask your doctor plenty of questions about how to manage it at your next visit.