Symptoms, Complications And The Long-Term Course Of A Cholesterol Lump In The Achilles Tendon: What Lowering Cholesterol Does To It, And What Surgery Can Achieve
A xanthoma of the Achilles tendon is a firm, usually painless cholesterol deposit that thickens the tendon above the heel, often on both sides. It’s a classic sign of familial hypercholesterolemia. Most cause few symptoms, but larger ones can affect how the ankle works. Studies show strong cholesterol lowering can shrink tendon xanthomas modestly, and surgery is reserved for lumps that cause real problems.
A xanthoma of the Achilles tendon is a cholesterol-filled thickening of the tendon, usually painless and often on both ankles, that strongly suggests familial hypercholesterolemia. Intensive cholesterol lowering can shrink tendon xanthomas by about 5% over around three years. Surgery is kept for large, symptomatic lumps and may need tendon reconstruction.
Key Takeaways
- Achilles tendon xanthomas are usually painless and often affect both ankles.
- They’re a hallmark of familial hypercholesterolemia, which raises heart risk.
- Statins reduced tendon thickness only where the tendon’s structure was still normal.
- Adding PCSK9 inhibitors shrank tendon xanthomas by about 5% over around three years.
- Large xanthomas can impair ankle function and may need surgery with tendon repair.
- Managing cholesterol comes first; it protects your heart and your relatives can be tested.
On This Page 17 sections
What Is A Xanthoma Of The Achilles Tendon?
It’s a deposit of cholesterol-filled cells inside the Achilles tendon, the thick cord connecting the calf muscles to the heel. It thickens the tendon or forms a firm lump and usually points to long-standing high LDL cholesterol.
Xanthomas are yellowish fatty deposits in the skin or around tendons. They’re noncancerous and painless, but they may signal another condition, and those next to tendons often don’t change the color of the skin above them.[5] In the Achilles tendon, years of high LDL cholesterol lead to deposits that immune cells take up, becoming foam cells within the tendon.
The most common cause is familial hypercholesterolemia (FH), an inherited condition that causes high LDL from birth.[1] This page focuses on symptoms, how these lumps change over time and what can be done. Our sister pages on xanthoma on the Achilles tendon (how they’re found) and Achilles tendon xanthoma cover other angles.
What Are The Symptoms Of A Xanthoma Of The Achilles Tendon?
Often none beyond a firm, painless thickening above the heel, usually on both sides. Larger ones can rub on shoes, feel bulky or gradually limit how well the ankle moves.
- A firm thickening or lump. Felt a few centimeters above the heel.
- Both ankles. In one surgical series, 75% of patients had both tendons affected.[4]
- Normal-looking skin. Tendon xanthomas often don’t change skin color.[5]
- Usually painless. Even as function changes, pain is often absent.[4]
- Footwear rubbing or stiffness. More likely as lumps grow.
Many are too small to feel at all; one study found ultrasound detected them in 60% of people with high LDL, against 23% by examination.[6] Our guides to tendon xanthomas and xanthoma of the tendon describe other common sites.
How Does A Xanthoma Of The Achilles Tendon Change Over Time?
Without good cholesterol control, it tends to enlarge slowly. With strong cholesterol lowering, growth can stop and some tendon xanthomas shrink a little.
Surgeons describe symptomatic Achilles tendon xanthomas as causing progressive enlargement of the tendon and painless loss of function.[4] In a three-year study of people with FH, tendon xanthomas grew by about 3 to 4% in those on statins with or without ezetimibe, but shrank by about 5% in those who also took PCSK9 inhibitors, which lowered LDL much further.[3] The lesson: how low your LDL goes affects what the lump does next.
It also helps to know that tendon changes build up over many years, so they also take time to respond. A lump that stays the same size on good cholesterol control is often a sign the medicine is doing its job, not that it has failed. Repeat ultrasound scans, done the same way each time, are the most reliable way to judge real change, because small differences are hard to feel by hand.
What Else Can Make The Achilles Tendon Thick Or Lumpy?
Overuse injuries, inflammation, gout and other conditions can also thicken the tendon, so a doctor’s examination, an ultrasound and blood tests are what tell them apart.
A xanthoma is one of several possible causes, and self-diagnosis isn’t reliable. Clues that point toward a xanthoma include a firm thickening on both sides that has developed slowly without an injury, high cholesterol, and a family history of high cholesterol or early heart disease. Sudden pain, redness, heat or swelling after an injury points elsewhere and should be checked promptly. Our page on skin xanthomas shows how other xanthomas look.
What Does An Ultrasound Show In A Xanthoma Of The Achilles Tendon?
A thicker tendon than normal, and sometimes changes in its internal structure: a patchy, uneven pattern or distinct darker spots where xanthoma tissue has built up.
A Greek study scanned the Achilles tendons of 80 people with FH and 80 matched controls. Tendons averaged 5.23 mm thick in the FH group against 4.20 mm in controls. On ultrasound, 42 people with FH had a normal tendon structure, 30 had a diffuse, uneven pattern and 8 had focal darker lesions, and tendon thickness rose with each grade, to an average of 6.98 mm in the last group.[2]
The authors suggested ultrasound is useful both for finding tendon involvement and for tracking how it responds over time.[2]
Tendon Structure And Response To A Statin (Greek Study, 12 Months)
| Ultrasound Grade | People | Average Thickness | After 12 Months Of Atorvastatin |
|---|---|---|---|
| Grade 1: normal structure | 42 | 4.90 mm | Fell to 4.50 mm |
| Grade 2: diffuse, uneven pattern | 30 | 5.20 mm | No significant change |
| Grade 3: focal darker lesions | 8 | 6.98 mm | No significant change |
| Controls without FH | 80 | 4.20 mm | Not applicable |
Can Lowering Cholesterol Shrink A Xanthoma Of The Achilles Tendon?
Somewhat, and earlier is better. A statin reduced tendon thickness only where the tendon’s structure was still normal, while adding PCSK9 inhibitors shrank established tendon xanthomas by about 5% over around three years.
In the Greek study, 12 months of atorvastatin (average 20 mg a day) reduced Achilles thickness from 4.90 mm to 4.50 mm in people whose tendons still looked structurally normal, but not in those whose tendons already showed xanthoma changes.[2]
A Spanish study of 48 people with FH and tendon xanthomas compared adding a PCSK9 inhibitor (alirocumab or evolocumab) to high-dose statins, with or without ezetimibe, against statins alone. LDL fell by about 81% versus 57%. Over an average of nearly three years, xanthoma thickness fell by about 5% with PCSK9 inhibitors but rose by about 3 to 4% without them.[3] It was a small, non-randomized study, but it supports the idea that very low LDL can reverse some tendon deposits.
Our guide to how each type of xanthoma is managed compares tendon xanthomas with other types.
What Complications Can A Xanthoma Of The Achilles Tendon Cause?
Most cause none. Large ones can enlarge the tendon, impair ankle movement and rub on footwear, and the high cholesterol behind them raises the risk of early heart disease.
- Loss of function. Progressive enlargement can cause painless functional impairment.[4]
- Reduced ankle movement. Before surgery, the series recorded limited ankle bending in both directions.[4]
- Footwear problems. Bulky lumps can rub against shoe backs.
- Heart risk. FH that isn’t managed leads to early coronary events in many people.[1]
When Is Surgery Needed For A Xanthoma Of The Achilles Tendon?
Only for large, symptomatic xanthomas that impair function, cause pain or cause persistent footwear problems despite cholesterol control. Because removing the deposit can leave a gap in the tendon, the tendon may need to be rebuilt.
MedlinePlus notes that bothersome xanthomas can be removed surgically and may return afterwards.[5] With the Achilles, excision can leave a tendon defect, which surgeons may repair by transferring a nearby tendon, the flexor hallucis longus.[4] This is a significant operation on a weight-bearing tendon, best planned with a foot and ankle or orthopedic surgeon, and always alongside cholesterol management.
What Are The Results Of Surgery For A Xanthoma Of The Achilles Tendon?
In a small 2026 series of eight patients who had the xanthoma removed and a tendon transfer, foot and ankle function scores improved markedly and pain dropped, with some wound problems along the way.
The patients averaged 31.6 years old; 62.5% had raised blood fats. Their foot and ankle function score (AOFAS) rose from 51.8 to 89.1 out of 100, pain scores fell from 7.0 to 1.6 out of 10, and ankle movement improved. One patient each (12.5%) had a seroma, a superficial wound infection, delayed wound healing or persistent weakness pointing the foot down, and no re-ruptures or repeat operations were seen during follow-up.[4] With only eight patients, these results are encouraging but preliminary.
What Is The Link With Familial Hypercholesterolemia?
Achilles tendon xanthomas are one of the classic signs of familial hypercholesterolemia, an inherited condition affecting about 1 in 250 to 1 in 500 people that raises LDL cholesterol from birth.
GeneReviews describes tendon xanthomas on the Achilles tendons, elbows, hands, knees and feet, along with xanthelasma, as signs of FH. When FH isn’t managed, about 50% of men had a coronary event by 50 and about 30% of women by 60, and statins are the first-line medicine.[1] Our page on whether xanthelasma is genetic explains how FH runs in families.
What Does It Mean For Your Family?
If FH is behind it, each of your children has a 50% chance of inheriting it, and your parents and siblings may have it too, so cholesterol testing for close relatives is important.
FH is autosomal dominant, meaning one altered gene from one parent is enough.[1] Finding it early lets relatives start managing their cholesterol before it affects their hearts. If a genetic test confirms your FH variant, relatives can be tested for the same change.
Can You Stay Active With A Xanthoma Of The Achilles Tendon?
Usually, yes. Most people carry on as normal; if a lump rubs or the ankle feels stiff, footwear changes and advice from a physiotherapist or foot specialist can help.
- Softer heel counters. Shoes that don’t press on the back of the ankle.
- Heel pads or open-backed shoes. To reduce rubbing.
- Gradual training changes. Build up activity steadily rather than suddenly.
- Report new pain. Sudden pain, swelling or a snapping feeling needs prompt care.
Regular activity also supports healthy cholesterol and heart health, so staying active is worth the small adjustments. Our guide to tendon xanthomata covers lumps on other tendons.
When Should You See A Doctor?
For any firm, persistent thickening of the Achilles tendon, and promptly if you have a family history of high cholesterol or early heart disease, or new pain, swelling or chest symptoms.
- A tendon lump or thickening. Ask for blood tests and, ideally, an ultrasound.[6]
- High cholesterol or early heart disease in the family. Ask about FH.[1]
- Function getting worse. Difficulty walking, running or climbing stairs.[4]
- Sudden pain or a snap at the back of the ankle. Seek urgent care.
- Chest pain or breathlessness. Seek care promptly.
What Should You Ask Your Doctor?
Ask about your cholesterol numbers and target, whether FH is likely, whether an ultrasound would help track the tendon, and when a surgical opinion would make sense.
- What’s my LDL, and what’s my target?
- Is familial hypercholesterolemia likely, and should I have a genetic test?
- Would an ultrasound help, now and to track changes? The Greek researchers suggested it’s useful for monitoring.[2]
- Is my current medicine lowering LDL enough? Stronger lowering was linked with xanthoma shrinkage.[3]
- At what point would surgery be worth discussing?
- How should my relatives be tested?
What’s The Bottom Line On Xanthoma Of The Achilles Tendon?
A xanthoma of the Achilles tendon is a firm, usually painless cholesterol thickening, often on both ankles, that points to familial hypercholesterolemia. Strong cholesterol lowering can stop growth and shrink some deposits, especially early. Surgery is for large, symptomatic lumps and may need tendon repair. Protecting your heart, and testing your relatives, matters most.
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 our pages on tendon xanthoma and xanthomatosis go further. You can also browse all our xanthelasma and xanthoma guides.
Common Questions About Xanthoma Of The Achilles Tendon
Is A Xanthoma Of The Achilles Tendon Painful?
Usually not. Most are painless, though large ones can rub on shoes or gradually limit ankle movement.
Does It Usually Affect Both Ankles?
Often, yes. In one surgical series, 75% of patients had both Achilles tendons affected.
Can Statins Shrink A Xanthoma Of The Achilles Tendon?
In one study, a statin reduced tendon thickness only where the tendon’s structure was still normal, so earlier control helps more.
Can Stronger Cholesterol Lowering Help?
Yes. Adding PCSK9 inhibitors to statins shrank tendon xanthomas by about 5% over around three years, while they grew slightly without them.
What Complications Can It Cause?
Large ones can enlarge the tendon, reduce ankle movement and rub on footwear, and the high cholesterol behind them raises heart risk.
When Is Surgery Needed?
Only for large, symptomatic xanthomas that impair function or cause persistent problems, and the tendon may need to be rebuilt afterwards.
How Well Does Surgery Work?
In a small series of eight patients, function scores rose from 51.8 to 89.1 and pain fell from 7.0 to 1.6, with some wound complications.
Does It Mean I Have Familial Hypercholesterolemia?
It strongly suggests it, but blood tests and often genetic testing confirm the diagnosis.
Sources
- Ison HE, Clarke SL, Knowles JW. Familial Hypercholesterolemia. GeneReviews, National Library of Medicine (NCBI Bookshelf), revised 2025.
- Tsouli SG, Xydis V, Argyropoulou MI, Tselepis AD, Elisaf M, Kiortsis DN. Regression of Achilles tendon thickness after statin treatment in patients with familial hypercholesterolemia: an ultrasonographic study. Atherosclerosis, 2009;205(1):151-155.
- 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.
- Choudhury ME, Arifeen KMN, Selimullah AZM, Chowdhury AZ, Faisal MA, Mahmud CI, Paul MS, Ferdous L, Rawal P. Functional Outcomes of Flexor Hallucis Longus Tendon Transfer after Excision of Achilles Tendon Xanthoma: A Case Series. Bangladesh Journal of Medical Science, 2026;25(4):1346-1353.
- Xanthoma. MedlinePlus Medical Encyclopedia, National Library of Medicine, reviewed April 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.
