A Site-By-Site And Cause-By-Cause Guide To Cholesterol Lumps In The Tendons: Hands, Elbows, Knees And Feet, And The Three Inherited Conditions Behind Them
A tendon xanthoma is a firm, usually painless deposit of fat-filled cells inside a tendon, most often the Achilles, the tendons over the knuckles, or those at the elbows and knees. The skin over it usually looks normal. Tendon xanthomas almost always point to an inherited condition: most often familial hypercholesterolemia, and rarely cerebrotendinous xanthomatosis or sitosterolemia, each managed differently.
Tendon xanthomas are firm cholesterol lumps in tendons, typically the Achilles, knuckles, elbows, knees and feet. They’re a hallmark of familial hypercholesterolemia, which affects about 1 in 250 to 1 in 500 people. Rarer causes include cerebrotendinous xanthomatosis and sitosterolemia. A doctor’s assessment and blood tests are essential.
Key Takeaways
- Tendon xanthomas are firm, usually painless lumps with normal skin over them.
- Common sites are the Achilles, knuckles, elbows, knees and feet.
- Familial hypercholesterolemia is the usual cause and raises heart risk.
- Cerebrotendinous xanthomatosis and sitosterolemia are rare inherited causes.
- Sitosterolemia xanthomas usually begin in childhood.
- Strong cholesterol lowering can shrink tendon xanthomas modestly.
On This Page 19 sections
What Is A Tendon Xanthoma?
It’s a deposit of fat-filled immune cells within a tendon, causing a firm, smooth thickening or lump. It’s usually painless and the skin over it looks normal, but it’s an important sign of an underlying lipid condition.
MedlinePlus describes xanthomas as yellowish fatty deposits that can appear anywhere, most often on the elbows, joints, tendons, knees, hands, feet or buttocks, noting that those next to tendons don’t change the color of the skin.[1] In a tendon, years of excess cholesterol (or, in rare conditions, other sterols) build up and are taken up by immune cells that become foam cells.
Spanish researchers studying 377 people with genetically confirmed familial hypercholesterolemia describe tendon xanthomas as a characteristic hallmark of that condition.[5] Our guides to tendon xanthomas, tendon xanthoma and tendon xanthomata cover the topic from other angles.
Where Do Tendon Xanthomas Form?
Most often in the Achilles tendons, the tendons over the knuckles and backs of the hands, and around the elbows, knees and feet, frequently on both sides of the body.
GeneReviews lists the Achilles tendons, elbows, hands, knees and feet as typical sites in familial hypercholesterolemia.[2] In sitosterolemia, MedlinePlus Genetics describes xanthomas on the heels, knees, elbows and buttocks and in tendons including those of the hand and the Achilles.[4]
- Achilles tendons. The classic and most studied site.
- Knuckles and backs of the hands. The extensor tendons that straighten the fingers.
- Elbows. Around the tendon at the back of the elbow.
- Knees. Around the tendons below the kneecap.
- Feet. Along tendons on the top of the foot.
What Do Tendon Xanthomas Look Like On The Hands?
Firm, smooth bumps over the knuckles or along the backs of the fingers and hand, which move when you bend and straighten your fingers. The skin over them usually looks normal.
The tendons on the back of the hand sit just under the skin, so even small xanthomas can be visible as knobbly knuckles. Making a fist and then spreading your fingers shows whether a lump moves with the tendon. Sitosterolemia specifically lists hand tendons among its sites.[4] Yellow streaks in the palm creases are a different type, palmar xanthomas; our page on palmar xanthoma explains them.
What About Tendon Xanthomas On The Elbows And Knees?
Lumps in the tendons around the elbows and knees are firm and move with the tendon. They can be confused with tuberous xanthomas, which sit in the skin over those joints.
Both types can appear in the same areas and both point to lipid conditions, so a doctor will usually examine them together. Large lumps at the knees and elbows can press on clothing or make kneeling or leaning uncomfortable, and in sitosterolemia large xanthomas can cause pain and movement difficulty.[4] Our guide to tuberous xanthoma explains the skin type.
What About The Feet And Achilles Tendons?
The Achilles is the classic site, often thickened on both sides. Many Achilles xanthomas are too small to feel and show up only on ultrasound.
Because the Achilles is weight-bearing and easy to scan, it’s the tendon doctors look at most. In the 2024 Spanish study, ultrasound measured a median maximum Achilles thickness of 5.50 mm in people with FH.[5] We have three dedicated pages: how Achilles xanthomas are found, their symptoms and long-term course, and Achilles tendon xanthoma.
Why Do Xanthomas Form In Tendons?
Because years of very high LDL cholesterol, or in rare conditions other sterols, let fat particles build up in tendon tissue, where immune cells take them up and turn into foam cells.
In the 2024 study of 377 people with FH, age, male sex, LDL cholesterol and lipoprotein(a) were each independently linked with thicker Achilles tendons, but together explained only about 20% of the differences between people.[5] Their mean LDL before any medicine was 277 mg/dL.[5] In other words, high LDL over many years is the key, but individual factors decide how much shows in the tendons. Our page on what xanthomas are explains how fatty deposits form.
How Is Familial Hypercholesterolemia Linked To Tendon Xanthomas?
It’s by far the most common cause. FH is an inherited condition that raises LDL cholesterol from birth, and tendon xanthomas are one of its classic signs, along with xanthelasma.
GeneReviews puts FH at about 1 in 250 to 1 in 500 people. It’s autosomal dominant, so each child of an affected parent has a 50% chance of inheriting it. When it isn’t managed, about 50% of men had a coronary event by 50 and about 30% of women by 60, and statins are first-line medicine.[2] Our page on whether xanthelasma is genetic explains the eyelid sign that often comes with it.
What Is Cerebrotendinous Xanthomatosis?
A rare inherited disorder of bile acid production that causes tendon xanthomas in the teens to twenties, often with normal cholesterol, after childhood cataracts and diarrhea, and before neurological problems in adulthood.
GeneReviews describes it as caused by changes in the CYP27A1 gene, inherited recessively. Typical features are diarrhea in infancy, cataracts in childhood in about 75%, tendon xanthomas in the teens to twenties and neurological decline in adulthood. It’s managed with chenodeoxycholic acid, a bile acid medicine, and early care appears to prevent symptoms.[3] That makes spotting it early especially valuable.
What Is Sitosterolemia?
A rare inherited condition in which plant sterols from foods such as vegetable oils and nuts build up in the blood and tissues, causing xanthomas that usually begin in childhood and early hardening of the arteries.
MedlinePlus Genetics explains that blood levels of sitosterol, the main plant sterol, can be 30 to 100 times normal. Cholesterol is often mildly to moderately raised, sometimes markedly in children, but can be normal. Xanthomas usually start in childhood, on the heels, knees, elbows, buttocks and in tendons, including those of the hand and the Achilles. Arterial plaque can begin in childhood, and some people have joint pain or blood changes such as early breakdown of red cells.[4]
It’s caused by changes in the ABCG5 or ABCG8 genes, which normally limit plant sterol absorption, and is inherited recessively. About 80 to 100 cases have been described, with an estimated prevalence of at least 1 in 50,000, and it’s likely underdiagnosed.[4]
Inherited Causes Of Tendon Xanthomas, Compared
| Condition | How Common | Inheritance | Key Clues |
|---|---|---|---|
| Familial hypercholesterolemia | About 1 in 250 to 1 in 500 | Dominant; 50% chance per child | Very high LDL, early heart disease in the family, xanthelasma |
| Cerebrotendinous xanthomatosis | Rare | Recessive (CYP27A1) | Childhood cataracts, infant diarrhea, later neurological symptoms |
| Sitosterolemia | At least 1 in 50,000 | Recessive (ABCG5 or ABCG8) | Xanthomas from childhood, very high plant sterols, sometimes normal cholesterol |
How Are Tendon Xanthomas Diagnosed?
With an examination of all the common sites, blood tests for cholesterol and other lipids, imaging if needed, and genetic or specialist tests to pin down which inherited condition is behind them.
- History. Your cholesterol, when the lumps appeared, eye or bowel problems in childhood, and family history.
- Examination. Achilles, knuckles, elbows, knees, feet and eyelids.
- Blood tests. Lipids, plus liver function and diabetes checks.[1]
- Imaging. Ultrasound of the Achilles tendons is the most common.
- Specialist tests. Genetic testing for FH, and specific tests for plant sterols or bile acid problems if the picture doesn’t fit.
- Biopsy. Occasionally, if the diagnosis is unclear.[1]
How Is The Cause Of Tendon Xanthomas Managed?
By managing the specific condition: cholesterol-lowering medicine for FH, chenodeoxycholic acid for cerebrotendinous xanthomatosis, and specialist care for sitosterolemia. Strong cholesterol lowering can shrink FH tendon xanthomas a little.
Statins are first-line for FH.[2] In a Spanish study of 48 people with FH and tendon xanthomas, adding a PCSK9 inhibitor to high-dose statins, with or without ezetimibe, lowered LDL by about 81% versus 57%, and over nearly three years tendon xanthomas shrank by about 5% instead of growing by 3 to 4%.[6] Cerebrotendinous xanthomatosis has its own medicine, chenodeoxycholic acid.[3] Sitosterolemia needs a different approach because the problem is plant sterols, so specialist guidance matters. Our guide to how each type of xanthoma is managed compares the options.
Can Tendon Xanthomas Be Removed?
Yes, surgically, but only for large, painful or movement-limiting lumps, and they may return. Managing the underlying condition always comes first.
MedlinePlus notes that bothersome xanthomas can be removed surgically or with laser and may return after surgery.[1] Because these deposits sit within tendons, surgery can affect how the tendon works and is best planned with an orthopedic or hand surgeon. Never try to remove, squeeze or inject a tendon lump yourself.
Can Children And Young Adults Get Tendon Xanthomas?
Yes. In sitosterolemia they usually start in childhood, in cerebrotendinous xanthomatosis they appear in the teens to twenties, and FH can cause them early too. Tendon lumps in a young person always deserve specialist assessment.
- Sitosterolemia. Xanthomas usually begin in childhood.[4]
- Cerebrotendinous xanthomatosis. Tendon xanthomas in the teens to twenties, often after childhood cataracts.[3]
- Familial hypercholesterolemia. High LDL is present from birth.[2]
Our guide to xanthomatosis covers conditions that cause many xanthomas at once.
What Do Tendon Xanthomas Mean For Your Family?
All three main causes are inherited, so relatives may be affected. With FH each child has a 50% chance; with the recessive conditions, brothers and sisters are most at risk.
FH passes from one parent with a 50% chance to each child.[2] Sitosterolemia and cerebrotendinous xanthomatosis are recessive: parents usually carry one altered copy without signs, and siblings of an affected person may also be affected.[3][4] A genetic diagnosis makes testing relatives much simpler.
When Should You See A Doctor?
For any firm, persistent lump on a tendon, and promptly if you also have very high cholesterol, early heart disease in the family, or the lumps appeared in childhood or with cataracts or nerve symptoms.
What Should You Ask Your Doctor About Tendon Xanthomas?
Ask which condition is most likely behind your lumps, which tests will confirm it, what your cholesterol target should be, and how your relatives should be checked.
- Which condition do you think this is? FH, cerebrotendinous xanthomatosis or sitosterolemia each need a different plan.
- Should I have genetic testing? It can confirm the cause and makes family testing straightforward.
- Do I need plant sterol or bile acid tests? Especially if my cholesterol is normal or the lumps started young.[4]
- What’s my LDL target, and is my medicine reaching it? Stronger lowering was linked with xanthoma shrinkage.[6]
- Would an ultrasound help track my tendons?
- Should I see a lipid specialist or geneticist? Rare causes are best managed by experienced teams.
- How should my children, siblings and parents be tested?
Bringing a list of which tendons are affected, when you first noticed each lump, and any family history of high cholesterol, early heart attacks, cataracts or nerve problems will make the appointment far more useful. Photos of the lumps over time help too.
What’s The Bottom Line On Tendon Xanthomas?
Tendon xanthomas are firm, usually painless lumps in the Achilles, knuckles, elbows, knees and feet. They almost always point to an inherited condition, most often familial hypercholesterolemia, and rarely cerebrotendinous xanthomatosis or sitosterolemia. Getting the right diagnosis protects your heart, guides the right medicine and helps your relatives.
For yellow patches on the eyelids, which can come with FH, see our guide to xanthelasma. Our pillar guide to xanthomas covers every type, and our page on skin xanthomas shows the skin forms. You can also browse all our xanthelasma and xanthoma guides.
Common Questions About Tendon Xanthomas
What Is A Tendon Xanthoma?
It’s a firm, usually painless deposit of fat-filled cells within a tendon, with normal-looking skin over it.
Where Do Tendon Xanthomas Appear?
Most often in the Achilles tendons, over the knuckles and backs of the hands, and around the elbows, knees and feet.
What Causes Tendon Xanthomas?
Usually familial hypercholesterolemia; rarer causes are cerebrotendinous xanthomatosis and sitosterolemia.
Do Tendon Xanthomas Mean I Have High Cholesterol?
Usually, but not always. Cerebrotendinous xanthomatosis and sitosterolemia can occur with normal cholesterol, so specialist tests matter.
What Is Sitosterolemia?
A rare inherited condition in which plant sterols build up in the blood, causing xanthomas from childhood and early arterial plaque.
Can Tendon Xanthomas Shrink?
Somewhat. In one study, adding PCSK9 inhibitors to statins shrank tendon xanthomas by about 5% over around three years.
Can Tendon Xanthomas Be Removed?
They can be removed surgically if large or troublesome, but this is rarely needed and they may return.
Should My Family Be Tested?
Yes. All the main causes are inherited, so relatives, especially children and siblings, may benefit from testing.
Sources
- Xanthoma. MedlinePlus Medical Encyclopedia, National Library of Medicine, reviewed April 2025.
- Ison HE, Clarke SL, Knowles JW. Familial Hypercholesterolemia. GeneReviews, National Library of Medicine (NCBI Bookshelf), revised 2025.
- Federico A, Gallus GN. Cerebrotendinous Xanthomatosis. GeneReviews, National Library of Medicine (NCBI Bookshelf), revised 2024.
- Sitosterolemia. MedlinePlus Genetics, National Library of Medicine, updated 2016.
- Corredoira P, Marco-Benedi V, Cenarro A, Peribáñez S, Olmos S, Civeira F. Factors associated with the presence of tendon xanthomas in familial hypercholesterolemia. Revista Española de Cardiología (English Edition), 2024;77(6):462-470.
- Bea AM, Perez-Calahorra S, Marco-Benedi V, Lamiquiz-Moneo I, Jarauta E, Mateo-Gallego R, Civeira F. Effect of intensive LDL cholesterol lowering with PCSK9 monoclonal antibodies on tendon xanthoma regression in familial hypercholesterolemia. Atherosclerosis, 2017;263:92-96.
