Tendon Xanthoma
Cholesterol Lumps in the Tendons: Where They Appear, What They Signal, and Why They Matter
A tendon xanthoma is a firm cholesterol deposit within a tendon, most often the Achilles, hands, knees, or elbows. This page explains the sites they affect, the inherited cholesterol disorders they signal, and why they always warrant a medical check.
By Xanthelasma.com
What Is a Tendon Xanthoma?
A tendon xanthoma (or tendinous xanthoma) is a deposit of cholesterol-rich material that builds up within a tendon, forming a firm, usually painless nodule or thickening. It develops when low-density lipoprotein (LDL) cholesterol accumulates in the tendon and immune cells absorb it, becoming the foam cells that make up the lump. The overlying skin usually looks normal, and the nodules tend to enlarge slowly over time.
While the lumps themselves are benign, tendon xanthomas are one of the most significant types of cholesterol deposit, because they are strongly tied to high cholesterol and inherited lipid disorders. Unlike the eyelid form (xanthelasma), which is often just cosmetic, a tendon xanthoma is an important medical sign that should prompt a cholesterol check. If you were looking for information on the yellow eyelid marks instead, our xanthelasma overview is the page you want. This page covers tendon xanthomas, which are a matter for medical care. Our xanthomas overview sets them in the wider family.
Where Tendon Xanthomas Appear
Tendon xanthomas have characteristic sites, and knowing them helps with recognition. By far the most common location is the Achilles tendon at the back of the ankle, where the lumps often appear on both sides symmetrically. They also commonly affect the extensor tendons on the backs of the hands and knuckles, and the tendons over the knees and elbows. They tend to be firm, slow-growing, and frequently appear in more than one place.
The lumps are usually painless, particularly early on, and are often noticed as a thickening felt under the skin rather than because they cause discomfort. As they grow, depending on location, they can occasionally restrict joint or tendon movement or cause discomfort against footwear or with activity. Because the Achilles is both the most common site and the one most likely to cause practical problems, we cover it in detail on dedicated pages: see Achilles tendon xanthoma, its cholesterol-marker significance, and its symptoms and complications. Our tendon xanthomas page gives a further overview.
What Tendon Xanthomas Signal
The real importance of tendon xanthomas is what they reveal about your cholesterol. They form because of persistently high LDL cholesterol over time, so their presence is a strong pointer to a lipid disorder, and very often to an inherited one. The classic association is familial hypercholesterolemia (FH), a genetic condition that causes very high LDL cholesterol from an early age; tendon xanthomas are one of its recognised physical signs, and finding them can lead to an FH diagnosis that protects the heart.
This matters because untreated high cholesterol, especially the inherited forms, substantially raises the risk of early cardiovascular disease, yet it is very treatable once identified. So a tendon xanthoma works as a valuable early warning. Because these conditions run in families, identifying one in you often means relatives benefit from screening too. Less commonly, tendon xanthomas can point to rarer inherited disorders, which is why xanthomas in unusual spots warrant specialist evaluation. Our pages on whether xanthelasma is genetic and skin xanthomas cover the inherited and lipid angles further.
The Rarer Inherited Causes
While familial hypercholesterolemia is by far the most common disorder behind tendon xanthomas, a doctor will sometimes consider rarer inherited conditions, particularly when the xanthomas appear in unusual places (such as the knees, elbows, or hands) or when other symptoms accompany them. Two examples are worth knowing about, mainly because they show why a proper medical work-up matters rather than because they are common.
Cerebrotendinous xanthomatosis (CTX) is a rare inherited disorder of bile acid metabolism in which tendon xanthomas can appear years before neurological symptoms; recognising the tendon sign early can allow treatment that changes the course of the disease. Sitosterolemia is another rare inherited condition affecting how the body handles plant sterols, which can produce tendon xanthomas in unusual sites and needs a distinct treatment approach. Neither is something to diagnose yourself, the point is simply that tendon xanthomas can reflect more than one underlying condition, which is exactly why medical assessment and blood testing are important. Our page on xanthomatosis covers CTX in more detail.
Diagnosis and How Tendon Xanthomas Are Managed
Diagnosis usually begins with a doctor examining the firm tendon nodules and taking a careful history, paying particular attention to any family history of high cholesterol or early heart disease. The central investigation is a lipid blood test to assess cholesterol levels, and genetic testing may follow where an inherited disorder like FH is suspected. Imaging (ultrasound or MRI) can confirm and characterise the deposits within the tendon, and occasionally a biopsy is used if the diagnosis is unclear. A doctor will also distinguish tendon xanthomas from other causes of tendon nodules, such as rheumatoid nodules or gout.
Management centres on the underlying cholesterol disorder rather than the lumps. That means lifestyle measures (a heart-healthy diet, regular activity, a healthy weight, not smoking) and, where appropriate, cholesterol-lowering medication such as statins, which protect cardiovascular health and can sometimes reduce the deposits over time. Surgery is reserved for xanthomas that are large, painful, or restrict movement, and is always paired with cholesterol management, since the lumps can recur if the lipids stay uncontrolled. This is firmly a doctor-led process and not something to treat at home. Our xanthoma treatment and what is xanthomas pages cover the wider approach.
Tendon Xanthoma: The Bottom Line
A tendon xanthoma is a firm cholesterol deposit within a tendon, most often the Achilles, but also the hands, knuckles, knees, and elbows, frequently appearing in more than one place. The lumps are benign, but their real significance is as a strong sign of high cholesterol, very often an inherited disorder such as familial hypercholesterolemia, and occasionally rarer conditions. That makes them a valuable prompt for a cholesterol check and assessment of cardiovascular risk.
Because of this, any firm tendon nodule, especially with a family history of high cholesterol or early heart disease, should be assessed by a doctor, who will check your lipids and manage the underlying cause, with surgery reserved for lumps causing physical problems. This is quite distinct from the cosmetic eyelid form. If the yellow eyelid marks were what you were searching for, our xanthelasma overview and xanthomas overview cover the wider picture.
Common Questions About Tendon Xanthomas
What is a tendon xanthoma?
A tendon xanthoma is a firm, usually painless deposit of cholesterol-rich material within a tendon, forming a nodule or thickening. It develops when LDL cholesterol accumulates in the tendon and immune cells absorb it, becoming foam cells. The overlying skin looks normal. Its main importance is as a sign of high cholesterol, often inherited.
Where do tendon xanthomas usually appear?
The most common site is the Achilles tendon at the back of the ankle, often on both sides. They also commonly affect the extensor tendons on the backs of the hands and knuckles, and the tendons over the knees and elbows. They are firm, slow-growing, and frequently appear in more than one place.
Are tendon xanthomas dangerous?
The lumps themselves are benign, but they are an important sign because they strongly indicate high cholesterol, very often an inherited disorder like familial hypercholesterolemia that raises cardiovascular risk. Larger ones can also occasionally restrict tendon or joint movement. So while the lumps are not dangerous in themselves, what they signal needs medical assessment.
Do tendon xanthomas mean I have high cholesterol?
Very often, yes. Tendon xanthomas form from persistently high LDL cholesterol and are strongly associated with lipid disorders, frequently inherited ones such as familial hypercholesterolemia. A lipid blood test is needed to confirm and is strongly recommended, because identifying and managing the cholesterol protects your cardiovascular health.
What is the link with familial hypercholesterolemia?
Familial hypercholesterolemia (FH) is an inherited disorder causing very high cholesterol from an early age. Because cholesterol stays high for years, it deposits in tendons, forming xanthomas. Tendon xanthomas are a recognised physical sign of FH, so finding one can lead to an important diagnosis and, because FH runs in families, screening for relatives.
Can tendon xanthomas be a sign of a rarer condition?
Occasionally. While familial hypercholesterolemia is the most common cause, rarer inherited disorders such as cerebrotendinous xanthomatosis (CTX) or sitosterolemia can also produce tendon xanthomas, particularly in unusual sites. This is one reason tendon xanthomas warrant proper medical assessment and blood testing rather than assumption, so the specific cause can be identified.
How are tendon xanthomas treated?
Treatment focuses on the underlying high cholesterol rather than the lumps, using lifestyle measures and lipid-lowering medication such as statins, which can sometimes reduce the deposits over time. Surgery is reserved for lumps that are large, painful, or restrict movement, and is always paired with cholesterol management to limit recurrence. It is a doctor-led process.
Should I see a doctor about a lump on my tendon?
Yes. Any firm, persistent nodule on a tendon, especially with a family history of high cholesterol or early heart disease, should be assessed. A doctor can confirm whether it is a xanthoma, check your cholesterol, identify any inherited disorder, and manage the underlying cause. This is not a condition to self-treat.
This page is for general information about tendon xanthomas and is not a substitute for medical advice. Tendon xanthomas are strongly linked to high cholesterol and to inherited lipid disorders such as familial hypercholesterolemia, so if you notice a firm lump on a tendon, please see a doctor for assessment, a lipid blood test, and management of any underlying cause.
