Tendon Xanthomas

What Are Tendon Xanthomas?

Tendon xanthomas are deposits of cholesterol-laden immune cells inside tendons. They appear as firm, painless, slowly growing swellings, most often on the Achilles tendons and the backs of the hands, and they usually point to an inherited lipid disorder.

Xanthomas are local deposits of lipid in body tissues. They’re usually benign in themselves but often signal a systemic condition. The tendinous type is a gradually progressive lesion of the Achilles tendon, elbows and the extensor tendons of the hands, and it’s strongly associated with familial hypercholesterolemia.^[1]

That strong link is what sets tendon xanthomas apart from many other xanthomas. Where eyelid xanthelasma often appears with normal blood fats, tendon xanthomas are usually a sign that something significant is happening with cholesterol. You’ll also see them called tendon xanthomata, and our single-lesion guide to a tendon xanthoma covers the basics.

Where Do Tendon Xanthomas Form?

Most often in the Achilles tendons at the back of the ankles and the extensor tendons on the backs of the hands and fingers. They also appear over the elbows, knees and the tops of the feet.

• Achilles tendons. The classic site, felt as thickening or lumps above the heel.^[1][2] See our guides to Achilles tendon xanthoma and xanthoma of the Achilles tendon.
• Hand extensor tendons. Lumps over the knuckles and the backs of the fingers that move with the tendons.^[1][2]
• Elbows. Over the back of the elbow.^[1][2]
• Knees and feet. Also listed among the typical sites in familial hypercholesterolemia.^[2]

These are tendons that take repeated strain, which may help explain why lipid gathers there. Achilles tendon xanthomas exposed to friction from footwear are the ones most likely to cause symptoms.^[1]

What Do Tendon Xanthomas Look And Feel Like?

Firm, smooth swellings or nodules that sit within a tendon and move with it. They’re usually skin-colored rather than yellow, because they’re deep, and they’re generally painless, though friction can make them sore.

Unlike eyelid xanthelasma or eruptive xanthomas, which sit in the skin and look yellow, tendon xanthomas lie deeper, so the skin over them usually looks normal. They grow slowly,^[1] and a thickened Achilles tendon can be easy to overlook until someone feels it.

For the raised skin type, see tuberous xanthoma; for the palm-crease type, palmar xanthoma.

How Do Tendon Xanthomas Form?

When cholesterol-carrying particles are high in the blood for years, they leak into the tendons. Immune cells take up the fat and become foam cells, which build up into a slowly growing deposit.

In people with raised blood fats, lipoproteins seep through the lining of blood vessels into the skin, the tissue beneath it and the tendons. Tissue macrophages engulf the lipid and become foam cells.^[1] Where the lipid comes from depends on the cause: usually LDL cholesterol in familial hypercholesterolemia, but unusual sterols in rarer disorders, such as cholestanol in cerebrotendinous xanthomatosis and sitosterol in beta-sitosterolemia.^[1]

Because the process takes years of exposure, tendon xanthomas usually appear from the second decade of life onward in people with a predisposing condition.^[1] Our guide to xanthomatosis explains what happens when xanthomas appear in many places.

Are Tendon Xanthomas A Sign Of Familial Hypercholesterolemia?

Very often, yes. About 75% of older adults with familial hypercholesterolemia have tendon xanthomas. The condition affects about 1 in 250 to 1 in 500 people, is inherited, and causes very high LDL cholesterol from birth.

About 75% of older adults with familial hypercholesterolemia have tendinous xanthomas.^[1] The condition affects about 1 in 500 to 1 in 250 people and is passed on in a dominant pattern, so each child of an affected parent has a 50% chance of inheriting it. Its physical signs include xanthelasma and tendon xanthomas on the Achilles tendons, elbows, hands, knees and feet.^[2]

It matters because, without management, about half of men with familial hypercholesterolemia have a coronary event by age 50, and about 30% of women by age 60.^[2] Statins are the first-line medicine.^[2] The inherited form is passed down families, which is why our guide on whether xanthelasma is genetic also covers it.

What Else Can Cause Tendon Xanthomas?

Read moreHow To Stop Xanthelasma From Growing

Rarer inherited conditions: cerebrotendinous xanthomatosis, which also affects the brain and eyes, and sitosterolemia, in which plant sterols build up. Both can cause tendon xanthomas even when cholesterol isn’t very high.

• Cerebrotendinous xanthomatosis (CTX). A rare recessive condition caused by changes in the CYP27A1 gene. It typically brings diarrhea in infancy, cataracts in childhood in about three-quarters of people, tendon xanthomas in the teens to twenties, and neurological decline in adulthood.^[3] It’s managed with chenodeoxycholic acid, and early care appears to prevent symptoms.^[3]
• Beta-sitosterolemia. Plant sterols such as sitosterol build up and can form xanthomas; people with unusual sterol deposits like these have a higher burden of hardened arteries.^[1]
• Other lipid disorders. Diabetes, an underactive thyroid and kidney disease can raise blood fats and lead to xanthomas,^[1] though tendon xanthomas point most strongly to an inherited cause.

Tendon xanthomas with normal or only modestly raised cholesterol, especially alongside cataracts, chronic diarrhea or neurological symptoms, are a reason for a doctor to consider CTX. Our xanthoma definition guide lists every type.

Are Tendon Xanthomas Dangerous?

The lumps themselves are benign, though they can rub and hurt. The danger is the condition behind them: familial hypercholesterolemia raises the risk of an early heart attack, and cerebrotendinous xanthomatosis can damage the nervous system if it isn’t caught.

Without management, about half of men with familial hypercholesterolemia have a coronary event by 50 and about 30% of women by 60.^[2] The outlook for anyone with xanthomas depends mainly on the underlying condition, and atheromatous deposits in the arteries often coexist with xanthomas.^[1] In cerebrotendinous xanthomatosis, neurological decline in adulthood is the main threat, which early care appears to prevent.^[3]

The lumps can cause local problems too: Achilles xanthomas rubbed by footwear can become sore, and they heal poorly after surgery.^[1] Our guide to xanthoma of the Achilles tendon covers the foot and ankle side.

How Are Tendon Xanthomas Diagnosed?

By examination, blood tests and sometimes imaging. A doctor feels the tendons, orders fasting cholesterol and triglyceride tests, and may use ultrasound to measure tendon thickness or MRI to rule out other causes.

1. Examination. Clinical examination is usually enough to identify the lesion; plain X-rays are typically normal.^[1]
2. Family and personal history. Early heart disease, high cholesterol or xanthomas in relatives.
3. Fasting blood tests. Triglycerides, total, LDL and HDL cholesterol, with glucose and HbA1c as indicated.^[1]
4. Imaging. Ultrasound can assess tendon xanthomas, and MRI helps rule out other conditions and plan surgery.^[1]
5. Specialist tests. Genetic testing for familial hypercholesterolemia, or tests for cholestanol or plant sterols if a rarer cause is suspected.^[1][2]
6. Biopsy. Excisional biopsy is used to rule out other diagnoses when needed.^[1]

How Are Tendon Xanthomas Managed?

Mainly by lowering cholesterol, which protects the heart and can shrink the lumps. Statins come first, with PCSK9 inhibitor injections for some people with familial hypercholesterolemia. Troublesome lumps can be removed surgically, alongside cholesterol control.

• Statins. The first-line medicine for familial hypercholesterolemia;^[2] they lower blood fats and may shrink xanthomas.^[1]
• PCSK9 inhibitors. Injectable medicines that are effective in familial hypercholesterolemia.^[1]
• Chenodeoxycholic acid. The medicine used for cerebrotendinous xanthomatosis.^[3]
• Lifestyle. Diet, activity, weight and not smoking all support cholesterol control and heart health.
• Surgery. For tendon xanthomas that hurt or rub on shoes, complete excision combined with medical control is preferred to reduce the chance of them coming back.^[1]

Surgery on the Achilles needs care, because the area heals poorly; careful handling of the tissue and closure techniques, sometimes including flaps, may be needed. Partial removal carries a high chance of the lump returning.^[1] Small xanthomas often shrink or resolve with control of the underlying disease.^[1]

Should Your Family Be Tested For Tendon Xanthomas?

Yes, if the cause is inherited. Each child of a parent with familial hypercholesterolemia has a 50% chance of having it, so parents, brothers, sisters and children should have their cholesterol checked, even without visible lumps.

Familial hypercholesterolemia is dominant, giving each child of an affected parent a 50% chance of inheriting it.^[2] Because it raises heart risk from birth and responds well to statins, finding affected relatives early makes a real difference. This process of testing relatives one by one is often called cascade screening.

Cerebrotendinous xanthomatosis is recessive, so it usually affects brothers and sisters rather than parents or children, and early care appears to prevent symptoms.^[3] A diagnosis in one family member is a reason to test siblings.

What If You Were Looking For The Eyelid Type?

Then you’re probably thinking of xanthelasma: soft yellow plaques near the inner corners of the eyelids. It’s far more common than tendon xanthomas, and about half of people with it have a lipid disorder.

Xanthelasma palpebrarum affects about 1.1% of women and 0.3% of men, and about half of people with it have a primary or secondary lipid disorder.^[4] It can occur alongside tendon xanthomas in familial hypercholesterolemia,^[2] and doctors look harder for an inherited lipid disorder when it appears in younger people.^[4] If you have both, mention it to your doctor.

Our main xanthelasma guide and what xanthelasma looks like cover the eyelid type in full.

When Should You See A Doctor About Tendon Xanthomas?

As soon as you notice them. Tendon lumps are a strong sign of a condition that’s important to find and manage early, and your family may need testing too.

• Book an appointment for any firm lump or thickening in your Achilles tendons, the backs of your hands, elbows or knees.
• Mention family history of high cholesterol, early heart attacks or strokes.
• Mention other symptoms such as cataracts at a young age, long-standing diarrhea, or problems with balance, memory or walking.
• Ask about referral to a lipid clinic for genetic testing and family screening.
• Seek urgent help for chest pain or other signs of a heart attack.

Sudden crops of small yellow-red bumps on the skin are a different type, described in our guide to eruptive xanthoma.

What’s The Bottom Line On Tendon Xanthomas?

Read moreXanthelasma Treatment

Tendon xanthomas are firm deposits of fat-filled cells in the tendons, most often the Achilles and the backs of the hands. They usually point to familial hypercholesterolemia, sometimes to rarer conditions, and they need a doctor’s assessment and a lipid test.

The lumps are benign, but the conditions behind them raise the risk of early heart disease or, in rare cases, nerve damage. Cholesterol-lowering medicine protects your heart and can shrink the lumps, and testing your family can find others who need care. If you were looking for yellow plaques on the eyelids instead, see our main xanthelasma guide, and browse all our xanthelasma and xanthoma guides.

Common Questions About Tendon Xanthomas

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