A tophus (plural: tophi) happens when crystals of the compound known as sodium urate monohydrate, or uric acid, builds up around your joints. Tophi often look like swollen, bulbous growths on your joints just under your skin.

Tophi are a symptom of gout, a condition where uric acid crystallizes in joints like those in your feet and hands.

Gout can cause episodes of severe pain called gout attacks. Without treatment, gout can become a chronic condition and increase your risk of developing tophi and joint damage.

With gout, tophi may not develop right away. Gout consists of four stages:

Asymptomatic hyperuricemiaYou have an abundance of uric acid in your blood (hyperuricemia), but don’t have any visible symptoms.
Acute goutBuildups of uric acid (or crystals) start forming in a joint, which can lead to severe inflammation and pain. This can make your joint warm to the touch (a gout attack).
Interval gout (intercritical)The symptomless stage between gout attacks. This stage can last for a few days or up to several months or years.
Chronic tophaceous goutThis is the stage where tophi develop in your joints and the tissues around them. They usually happen if you don’t treat your gout for a long time (about 10 years or more). Tophi may also form in your ears.

Gout results from uric acid buildup in your blood. Uric acid normally gets removed from your blood through your renal system in urine, but your diet or certain conditions can make it hard for your body to excrete uric acid. In this case, uric acid builds up around joints.

Tophi can form in any of the following body parts:

  • feet
  • knees
  • wrists
  • fingers
  • Achilles tendon
  • ears

Types of tissues where uric acid most commonly builds up to form tophi include:

  • tendons that connect joints to muscles
  • cartilage around your joints
  • synovial membranes that line your joint cartilage
  • any soft tissues in your joints, such as fat or ligaments
  • bursae, small sacs that create a cushion-like barrier between bones and other soft tissues

Tophi can also form in connective tissue that isn’t found in a joint. Some of these locations include:

  • sclerae, better known as the “whites” of your eyes
  • renal pyramids, which are triangular-shaped parts of your kidneys made up of ducts and nephrons that help absorb nutrients before releasing waste as urine
  • heart valves, such as the aorta (very rarely)

Tophi usually don’t cause pain on their own. But swelling can become painful, especially if tophi are actively inflamed.

When left untreated, tophi can break down joint tissue, making it harder and more painful to use those joints. This can make your joints look twisted.

Tophi can stretch out your skin and make skin uncomfortably tight, sometimes causing painful sores. When this happens, tophi can break open and release a soft, white material made of hardened uric acid.

Other common symptoms of a gout attack that may accompany tophi include:

  • swelling, tenderness, and warmth where the tophus is located
  • discomfort when using the affected joint or difficulty using it for days after the attack subsides
  • severe pain in the affected joint, especially in the few hours after the attack begins
  • losing range of motion in your affected joint, which can become more noticeable if your gout isn’t treated

Small tophi that don’t cause any pain or limit your movement may not need to be removed — you may just need to take certain medications or change your diet to shrink them.

Large tophi should be removed to prevent any damage to your joint or loss of its range of motion. Your doctor may recommend one of the following surgeries:

  • making a small cut on the skin above the tophus and removing it by hand
  • joint replacement surgery if the joint has become damaged and difficult to use

Some treatment options for gout that can help reduce your chances of developing tophi include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen sodium (Aleve) or ibuprofen (Advil). These help relieve pain and inflammation caused by gout attacks and joint damage from tophi.
  • Corticosteroids that reduce inflammation, injected directly into your joint or taken as an oral medication. Prednisone is one of the most common corticosteroids.
  • Xanthine oxidase inhibitors (XOIs) that reduce the amount of uric acid your body produces and decrease your chance of developing gout and tophi. These include febuxostat (Uloric) and allopurinol (Zyloprim).
  • Uricosurics that help your kidneys filter uric acid out of your blood. These include lesinurad (Zurampic) and probenecid (Probalan).

Gout can often be treated by making lifestyle changes, such as losing weight, exercising regularly, and drinking plenty of water (at least 64 ounces each day).

Consuming certain nutrients found in everyday foods can also help. Try one or more of the following:

  • Cherries. Eating cherries, even over a short period of time, can reduce the amount of gout attacks you experience. A 2012 study of 633 people with gout found that eating cherries for two days reduced their risk of gout attacks by 35 percent.
  • Vitamin C. This vitamin can help lower the amount of uric acid in your blood. It’s found in many citrus fruits, such as oranges, and can be taken as a dietary supplement pill or powder.
  • Coffee. Having a little coffee each day can also reduce your risk of developing gout.
  • Dairy products. According to one 1991 study, milk proteins appear to be able to lower levels of uric acid in your blood.

The plant-based treatment known as colchicine (Mitigare) can also help reduce pain caused by gout.

Gout should be treated as early as possible to prevent painful symptoms and complications caused by tophi. Even if you’ve only had one gout attack and it’s been a long time, you may simply be in the interval stage, and uric acid can still build up.

If your doctor finds increased uric acid levels in your blood, follow their instructions closely to reduce your levels to lower your risk of developing tophi and protect your joints from any damage or loss of motion.