Tophi are hardened lumps of monosodium urate (MSU) crystals—or uric acid—that are deposited in and around the joints of people with gout. While they are often painless, tophi (Latin: "stone") can erode bone and joints, destroy cartilage and lead to chronic inflammation and other longterm complications. Over time, they can cause deformities and disability, as it becomes harder to move the affected joints.
There are three stages of gout:
Asymptomatic hyperuricemia, in which you have no symptoms although uric acid crystals are starting to form around a joint
Interval gout, which is characterized by episodes of gout punctuated by asymptomatic periods
Chronic tophaceous gout, in which uric acid crystals develop into tophi chunks in and around the joints
When Tophi Form
Studies have shown that tophi appear an average of 11.6 years between the time someone experiences their first attack of gout and the chronic gouty arthritis phase .1
Why Tophi Form
The formation of these hardened chunks of uric acid tend to correlate with the severity and duration of hyperuricemia, or high levels of uric acid in the blood in people with gout. Tophaceous gout occurs because of the body's inability to eliminate urate as quickly as it is produced. As excess urate collects, urate crystal deposits can form to create tophi.
But while a high level of serum urate is the primary cause, there may be other factors that contribute to the formation of tophi, such as:
The onset of gout at an early age
Long periods of time in which the gout has been active but untreated
An average of four gout attacks each year
Upper extremity and polyarticular involvement of five or more joints
Tophi tend to develop in about 15% of people who have had gout for less than 10 years. Creatinine clearance, which is a measure of kidney damage, is an independent factor that has also been linked to early tophi formation.
Where Tophi Form
Tophi can be deposited in the cartilage, synovial membranes, tendons, and soft tissues. Though they can appear anywhere on the body, they tend to be most commonly found on the:
Renal pyramid of the kidneys
Sclera (white outer layer of the eyeball)
Characteristics of Tophi
Tophi are typically painless, but the acute inflammation that can develop around them may create considerable pain. They lead to destruction of the joints, resulting in deformity. This is especially prevalent on the hands and feet. The skin that lies over a tophus (singular) can become taut and eventually ulcerate. A white chalky or pasty substance, composed of urate crystals, may be expelled from the ulcerated deposit.
Typically, tophi are detected with ultrasonography, magnetic resonance imaging (MRI), or computed tomography (CT). But a CT scan will yield the most detailed and precise images.
Quality of Life
A 2012 study found that people who experienced both the presence of tophi and acute gout flare-ups had a decreased health-related quality of life.
A Word From Verywell
If you have gout, it is important to monitor your uric acid levels regularly—even during periods when you're asymptomatic and between attacks. Understandably, it's easy to stop paying attention during those times when the gout is dormant and you're pain-free. But if you manage gout properly at all times, you stand a better chance of successful longterm treatment. You can head off the decreased quality of life that may be experienced by people with tophi by pro-actively managing your hyperuricemia and gout.