Spotting A Cholesterol Lump On The Achilles Tendon: How To Check, Why Ultrasound Finds Far More Than Touch, And What It Means For You And Your Family
A xanthoma of the Achilles tendon is a firm, usually painless thickening or lump in the tendon at the back of the ankle, made of fat-filled cells. It’s one of the clearest physical signs of familial hypercholesterolemia, an inherited cause of very high LDL cholesterol that raises the risk of early heart disease. Many of these xanthomas are too small to feel, which is why ultrasound picks up far more than a hands-on check.
An Achilles tendon xanthoma is a cholesterol-filled thickening of the tendon above the heel, usually on both sides. It strongly suggests familial hypercholesterolemia, which affects about 1 in 250 to 1 in 500 people. In one study, examination found these xanthomas in 23% of people with high LDL, but ultrasound found them in 60%. See a doctor for blood tests.
Key Takeaways
- Achilles tendon xanthomas are firm, usually painless thickenings above the heel.
- They’re a hallmark of familial hypercholesterolemia (FH).
- Ultrasound found them in 60% of people with high LDL, versus 23% by touch.
- Adding ultrasound raised probable or definite FH diagnoses from 43% to 72%.
- Each child of a parent with FH has a 50% chance of inheriting it.
- Managing cholesterol is the priority; surgery is only for troublesome lumps.
On This Page 18 sections
What Is An Achilles Tendon Xanthoma?
It’s a deposit of fat-filled cells within the Achilles tendon, the thick cord at the back of the ankle, causing the tendon to thicken or form a lump. It usually signals long-standing high LDL cholesterol, most often from familial hypercholesterolemia.
Xanthomas are yellowish fatty deposits in the skin or around tendons. They’re noncancerous and painless, but they can signal another condition, and those next to tendons often don’t change the color of the skin above them.[5] In the Achilles tendon, cholesterol carried in the blood builds up over years, taken up by immune cells that become foam cells inside the tendon.
Researchers in a 2024 study of 377 people with genetically confirmed FH describe tendon xanthomas as a characteristic hallmark of the condition.[3] This page focuses on how they’re found and what they mean. Our sister pages on Achilles tendon xanthoma and xanthoma of the Achilles tendon cover the same lump from other angles, and our guide to tendon xanthomas covers every tendon.
What Does An Achilles Tendon Xanthoma Look And Feel Like?
A firm, smooth thickening or lump in the tendon a few centimeters above the heel, usually painless, often on both sides, with normal-colored skin over it.
- Feel. Firm and rubbery rather than soft; it moves with the tendon.
- Color. The skin usually looks normal, unlike yellow skin xanthomas.[5]
- Shape. From a subtle widening of the tendon to an obvious lump.
- Both sides. Often present in both Achilles tendons.
- Elsewhere. Similar lumps can appear on the elbows, hands, knees and feet.[1]
Small ones can’t be seen or felt at all, which is a key reason ultrasound matters. Our pages on tendon xanthoma and xanthoma tendon show other common sites.
How Can You Check Your Achilles Tendons?
Gently feel both tendons from the heel upward, comparing sides for any thickening, lumps or difference in width. A normal-feeling tendon doesn’t rule a xanthoma out, so mention any family history to your doctor.
- Sit with your feet relaxed. Let the tendons go slack.
- Pinch gently. Use your thumb and finger on each side of the tendon, starting just above the heel.
- Work upward. Feel along the cord for about a hand’s width.
- Compare sides. Note any widening, lump or firmness on one or both.
- Look at your other joints. Check the knuckles, elbows and knees for firm lumps.
- Tell your doctor. Especially with high cholesterol or early heart disease in the family.
Why Does Ultrasound Find More Achilles Tendon Xanthomas?
Because many are too small to feel. In one study, physical examination found them in 23% of people with high LDL, but ultrasound found them in 60%.
Swiss researchers examined 100 consecutive patients with LDL cholesterol of at least 4 mmol/L (about 155 mg/dL); the average age was 47. Trained physicians examined the tendons by hand, and a separate, blinded physician scanned them by ultrasound. Achilles tendon xanthomas were found in 23% by examination but in 60% by ultrasound.[2]
That difference changed diagnoses. Using the Dutch Lipid Clinic Network Score, a common FH scoring system in which tendon xanthomas count heavily, the share of patients classed as probable or definite FH rose from 43% to 72% when ultrasound was added.[2] The authors concluded ultrasound substantially improves detection and may help identify high-risk people more accurately.
What Is The Link With Familial Hypercholesterolemia?
Familial hypercholesterolemia (FH) is an inherited condition causing very high LDL cholesterol from birth. Years of high LDL lead to deposits in tendons, so Achilles xanthomas are one of its classic signs.
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. Signs include tendon xanthomas on the Achilles tendons, elbows, hands, knees and feet, and xanthelasma on the eyelids.[1]
In the 2024 Spanish study, people with genetically confirmed FH had a mean LDL of 277 mg/dL before any cholesterol-lowering medicine.[3] Our page on whether xanthelasma is genetic explains how FH runs in families and shows on the eyelids too.
What Affects How Thick The Achilles Tendon Becomes?
Age, being male, LDL cholesterol and lipoprotein(a) were each linked with thicker tendons in people with FH, but together they explained only about 20% of the differences between people.
The 2024 study measured the maximum thickness of the Achilles tendon by ultrasound in 377 people with FH; the median was 5.50 mm. Age, male sex, LDL cholesterol and lipoprotein(a), a genetically set blood fat, were independently associated with thickness, yet explained only about a fifth of the variation.[3]
In other words, two people with similar cholesterol can have very different tendons. That’s why the absence of a visible lump doesn’t rule FH out, and why a blood test, not the tendon alone, makes the diagnosis.
Can Achilles Tendon Xanthomas Have Another Cause?
Rarely, yes. Cerebrotendinous xanthomatosis, an inherited disorder of bile acid production, causes tendon xanthomas in the teens or twenties, often with normal cholesterol.
GeneReviews describes cerebrotendinous xanthomatosis 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.[4]
So tendon xanthomas in a young person, especially with a history of childhood cataracts or long-standing diarrhea, deserve a specialist look even if cholesterol is normal. Our guide to xanthomatosis covers conditions that cause many xanthomas.
Causes Of Achilles Tendon Xanthomas, Compared
| Cause | How Common | Cholesterol | Other Clues |
|---|---|---|---|
| Familial hypercholesterolemia | About 1 in 250 to 1 in 500 | Very high LDL from birth | Family history of high cholesterol or early heart disease; xanthelasma |
| Cerebrotendinous xanthomatosis | Rare | Often normal | Childhood cataracts, infant diarrhea, later neurological symptoms |
| Other lipid disorders | Varies | Raised | Lumps over elbows and knees, palm-crease streaks |
Does An Achilles Tendon Xanthoma Affect Walking?
Usually not. Most are painless and cause no trouble, though larger ones can rub on shoes or make the back of the ankle feel bulky.
If a lump rubs, softer heel counters, a heel pad or shoes with a lower back can help. Any new pain, swelling, redness or difficulty walking is worth getting checked, as it may be something other than the xanthoma itself. Our guide to tendon xanthomata covers lumps on other tendons and how they behave.
How Is An Achilles Tendon Xanthoma Diagnosed?
With a hands-on examination, an ultrasound scan of both tendons, and blood tests for cholesterol, often followed by genetic testing for FH.
- History. Your cholesterol results and any family history of high cholesterol or early heart attacks.
- Examination. Both tendons, plus knuckles, elbows, knees and eyelids.
- Ultrasound. Finds far more xanthomas than examination alone.[2]
- Blood tests. Lipids, plus liver function and diabetes checks.[5]
- FH scoring and genetic testing. Confirms the diagnosis and helps with family testing.[1]
How Is The Cholesterol Behind An Achilles Tendon Xanthoma Managed?
Mainly with cholesterol-lowering medicine, usually starting with a statin, alongside heart-healthy habits. The goal is protecting your heart; the lump is secondary.
Statins are the first-line medicine for FH.[1] Managing the underlying condition may help reduce new xanthomas.[5] Because the high LDL in FH is inherited and present from birth, medicine is usually central, sometimes more than one. Eating less saturated fat, staying active, keeping a healthy weight and not smoking all support the medicine. Our guide to how each type of xanthoma is managed compares tendon xanthomas with other types.
Can An Achilles Tendon Xanthoma Be Removed?
Yes, surgically, but it’s rarely needed. Surgery is reserved for large, painful or troublesome lumps, and xanthomas may return after surgery, especially if cholesterol isn’t controlled.
MedlinePlus notes that bothersome xanthomas can be removed surgically or with a laser, and may return after surgery.[5] Because the deposit sits inside a weight-bearing tendon, surgery here is a bigger decision than removing a skin lesion, and it’s best discussed with an orthopedic or foot and ankle surgeon. Never try to remove or inject a tendon lump yourself.
What Does An Achilles Tendon Xanthoma Mean For Your Family?
If it’s from FH, your parents, brothers, sisters and children may have it too. Each child of an affected parent has a 50% chance, so testing relatives can find FH before it affects their hearts.
- Tell close relatives. Parents, siblings and children.[1]
- Encourage cholesterol tests. A simple blood test is the first step.
- Consider genetic testing. If your FH gene change is known, relatives can be tested for it.
- Check children. Your doctor can advise when testing makes sense.
What Does An Achilles Tendon Xanthoma Mean For Your Heart?
It’s a sign your arteries may have been exposed to high LDL for years. With FH that isn’t managed, about half of men had a coronary event by 50 and about 30% of women by 60.
Those figures come from GeneReviews, which also identifies statins as first-line medicine.[1] The positive side is that FH found early and managed well carries a much better outlook. An Achilles xanthoma can be the clue that starts that process, for you and your relatives.
When Should You See A Doctor?
As soon as you notice a thickening or lump in either Achilles tendon, and promptly if you also have chest pain, a family history of early heart disease or yellow patches on your eyelids.
- Any tendon lump or thickening. Ask for blood tests and, ideally, an ultrasound.[2]
- A family history of high cholesterol or early heart attacks. Ask about FH.[1]
- Yellow patches on the eyelids too. Another sign that can come with FH.[1]
- A young person with tendon lumps and cataracts. Ask about cerebrotendinous xanthomatosis.[4]
- Chest pain or breathlessness. Seek care promptly.
What Should You Ask Your Doctor About An Achilles Tendon Xanthoma?
Ask for your full cholesterol results, whether FH is likely, whether an ultrasound or genetic test would help, what LDL target to aim for, and how your relatives should be tested.
- What are my LDL, HDL, triglyceride and lipoprotein(a) results? Lipoprotein(a) is linked with thicker tendons in FH.[3]
- How likely is familial hypercholesterolemia? Ask how your score was worked out.
- Would an ultrasound of my tendons help? It finds many xanthomas that can’t be felt.[2]
- Should I have genetic testing? It can confirm FH and guide family testing.[1]
- What’s my LDL target, and how will we get there? Including which medicines and how often to retest.
- Should I see a lipid specialist? Many areas have clinics for inherited cholesterol conditions.
- How should my children and siblings be checked? And at what age for children.
What’s The Bottom Line On Achilles Tendon Xanthoma?
An Achilles tendon xanthoma is a firm, usually painless cholesterol thickening above the heel and a hallmark of familial hypercholesterolemia. Many are too small to feel, so ultrasound finds far more. See a doctor for blood tests, manage the cholesterol to protect your heart, and encourage relatives to get checked. Surgery is only for troublesome lumps.
For yellow patches on the eyelids, which can also come with FH, see our guide to xanthelasma. Our pillar guide to xanthomas covers every type, including tuberous xanthoma and palmar xanthoma, and our page on skin xanthomas shows the skin types. You can also browse all our xanthelasma and xanthoma guides.
Common Questions About Achilles Tendon Xanthoma
What Is An Achilles Tendon Xanthoma?
It’s a firm, usually painless deposit of fat-filled cells in the Achilles tendon that thickens it or forms a lump above the heel.
Does An Achilles Tendon Xanthoma Mean I Have Familial Hypercholesterolemia?
It strongly suggests it, but a blood test and often genetic testing confirm the diagnosis; rarer conditions can also cause it.
Can You Feel An Achilles Tendon Xanthoma?
Not always. In one study, examination found them in 23% of people with high LDL, while ultrasound found them in 60%.
Is An Achilles Tendon Xanthoma Dangerous?
The lump itself is usually harmless, but it signals long-term high LDL cholesterol, which raises the risk of early heart disease.
How Is An Achilles Tendon Xanthoma Diagnosed?
With an examination, an ultrasound scan of both tendons, and blood tests for cholesterol, often followed by genetic testing.
How Is The Cholesterol Managed?
Usually with a statin as first-line medicine, alongside diet, activity, a healthy weight and not smoking.
Can An Achilles Tendon Xanthoma Be Removed?
It can be removed surgically if it’s large or troublesome, but this is rarely needed and it may return.
Should My Family Be Tested?
Yes, if it’s caused by familial hypercholesterolemia, because each child of an affected parent has a 50% chance of inheriting it.
Sources
- Ison HE, Clarke SL, Knowles JW. Familial Hypercholesterolemia. GeneReviews, National Library of Medicine (NCBI Bookshelf), revised 2025.
- de Montmollin M, Bétrisey S, Feller M, Moutzouri E, Blum MR, Amsler J, Papazoglou DD, Möller B, Rodondi N. Achilles tendon ultrasonography in the clinical screening of familial hypercholesterolaemia: a cross-sectional analysis. Swiss Medical Weekly, 2023;153(11):40127.
- 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.
- Federico A, Gallus GN. Cerebrotendinous Xanthomatosis. GeneReviews, National Library of Medicine (NCBI Bookshelf), revised 2024.
- Xanthoma. MedlinePlus Medical Encyclopedia, National Library of Medicine, reviewed April 2025.
