Xanthoma

Author: Vanessa Ngan, Staff Writer; Dr Amy Stanway, Dermatology Registrar, Nottingham, United Kingdom, 2005.


What is a xanthoma?

A xanthoma is a skin lesion caused by the accumulation of fat in macrophage immune cells in the skin and more rarely in the layer of fat under the skin.

Some types of xanthoma are indicative of lipid metabolism disorders (e.g. hyperlipidaemia or high blood fats), where they may be associated with increased risk of coronary artery heart disease and occasionally with pancreatitis.

Xanthomas are classified into the following types based on where they are found on the body and how they develop.

Xanthelasma palpebrum

  • Most common type of xanthoma
  • Lesions arise symmetrically on upper and lower eyelids
  • Lesions are soft, velvety, yellow, flat papules or plaques
  • Lesions start off as small bump and gradually grow larger over several months
  • May or may not be associated with hyperlipidaemia

See more images of xanthelasma ...

Xanthelasma

Tuberous xanthomas

  • Firm, painless, red-yellow nodules that develop around the pressure areas such as the knees, elbows, heels and buttocks
  • Lesions can join together to form multilobated masses
  • Usually associated with hypercholesterolaemia (increased cholesterol levels in blood) and increased LDL levels
Tuberous xanthoma

Tendinous xanthoma

  • Appears as slowly enlarging subcutaneous nodules related to a tendon or ligament
  • Most commonly found on the hands, feet, and Achilles tendon
  • Associated with severe hypercholesterolaemia and elevated LDL levels
Tendinous xanthoma

Eruptive xanthomas

  • Lesions typically erupt as crops of small, red-yellow papules
  • Most commonly arise over the buttocks, shoulders, arms and legs but may occur all over the body
  • Rarely the face and inside of the mouth may be affected
  • Lesions may be tender and usually itchy
  • Lesions may resolve spontaneously over a few weeks
  • Associated with hypertriglyceridaemia (increased triglyceride levels in blood) often in patients with diabetes mellitus (sugar diabetes)
Eruptive xanthomas

Plane xanthoma

  • Lesions are flat papules or patches that can occur anywhere on the body
  • Lesions on the creases of the palms are indicative of a specific pattern of increased lipids in blood called type III dysbetalipoproteinaemia
  • May be associated with hyperlipidaemia and hypertriglyceridaemia

Diffuse plane xanthomatosis

  • A rare form of histiocytosis.
  • Associated with an abnormal antibody in the blood called a paraprotein.
  • Lipid levels are normal.
  • About 50% will have a malignancy of the blood; usually multiple myeloma or leukaemia.
  • Presents with large flat reddish-yellow plaques over the face, neck, chest, buttocks and in skin folds (such as the armpits and groin).
Diffuse plane xanthomas

Xanthoma disseminatum

  • Xanthoma-like lesions due to a rare form of histiocytosis.
  • Lipid metabolism is normal.
  • The skin lesions usually consist of hundreds of small yellowish-brown or reddish-brown bumps, which are usually evenly spread on both sides of the face and trunk. They may particularly affect the armpits and groins.
  • The small bumps may join together to form sheets of thickened skin.
  • 30% of affected people have involvement of the lining of the mouth, airways or eyes (mucosal surfaces). Warty plaques in the mouth are called verruciform xanthomas.
  • 40% of affected people develop diabetes insipidus, a condition that results in inability to control water loss (resulting in continual thirst and excessive urine production). This is due to histiocyte overgrowth on the lining of the brain (meninges).
  • May affect internal organs (such as liver, lungs, kidneys etc.)
  • Self-limiting and eventually improves by itself but may persist for many years.
Xanthoma disseminatum

What causes xanthoma?

There are several underlying disorders in which xanthoma is caused by a disturbance in lipid (fat) metabolism. Because lipids are insoluble in water they combine with proteins to form compounds called lipoproteins. Lipoproteins transport lipids and cholesterol in the blood to different parts of the body. Depending on their size and weight, the common lipoproteins are classified as chylomicrons, very-low-density lipoproteins (VLDL), low-density-lipoproteins (LDL), and high-density-lipoproteins (HDL) (Fredrickson classification). They all have a role to play in maintaining metabolic functioning of the body.

Alterations in lipoproteins may be a result of a genetic defect (e.g. primary hyperlipoprotenaemia) or from some underlying systemic disorder such as diabetes mellitus, hypothyroidism, or nephrotic syndrome. These underlying diseases can cause elevated levels of certain lipids and lipoproteins, which then manifest as cutaneous xanthoma.

Monogenic familial hypercholesterolaemia: Type IIa

  • Mutation in LDL receptor
  • High levels of LDL
  • Total cholesterol in heterozygotes 9–14 mmol/L
  • Total cholesterol in homozygotes 15–30 mmol/L

Polygenic familial hypercholesterolaemia: Type IIa

  • Mixed genetic and lifestyle causes
  • Wide range of results

Polygenic familial combined hyperlipidaemia: Type IIb

  • Mixed genetic and lifestyle causes
  • Raised total cholesterol
  • Raised triglyceride
  • Low HDL cholesterol
  • Increased VLDL cholesterol
  • LDL may be normal level but denser and more likely to cause atheroma

Moderate hypertriglyceridaemia

  • Often also associated with high blood pressure, obesity, diabetes mellitus, high insulin levels, high uric acid levels
  • Can be due to alcohol, or medications such as systemic steroids, isotretinoin, acitretin
  • Triglycerides 2_10 mmol/L
  • Often associated with low HDL cholesterol

Severe hypertriglyceridaemia: Type 1 and V

  • Mixed genetic and lifestyle causes
  • Diabetes mellitus
  • Familial LPL deficiency
  • Triglycerides > 10 mmol/L
  • Raised total cholesterol
  • Raised chylomicrons
  • Raised VLDL cholesterol

Broad beta hyperliproteinaemia: Type III

  • Rare apo E gene mutation
  • Triglycerides 5–20 mmol/L
  • Total cholesterol 7–12 mmol/L

The reason for the appearance of xanthoma when the blood fats are normal is not understood at this time.

What work-up is required for xanthoma?

Appropriate blood and urine tests and X-rays are performed to determine the cause of disturbed lipoprotein levels if they are present. The risk of cardiovascular disease, including heart attacks, peripheral vascular disease and stroke, is increased with elevated levels of certain lipoproteins. It is essential to identify the contributing factors so that appropriate therapy can be established.

What is the treatment for xanthoma?

The main aim of treatment for xanthoma that is associated with an underlying lipid disorder is to identify and treat the lipid disorder. In many cases, treating the underlying disorder will reduce or resolve the xanthoma. In addition, treating hyperlipidaemia will reduce the risk of heart disease, and treating hypertriglyceridaemia will prevent pancreatitis. Dietary and lifestyle modifications with or without medication are used to treat lipid disorders.

Dietary measures should include:

  • Prepare most meals from vegetables, salads, cereals and fish
  • Minimise saturated fats (found in meat, butter, other dairy produce, coconut oil, palm oil)
  • Minimise intake of simple, refined sugars found in fizzy drinks, sweets, biscuits and cakes
  • If obese or overweight, aim to slowly reduce weight by reducing caloric intake and increasing exercise.

Very effective medications may also be prescribed. These may include:

  • Statins (HMG CoA reductase inhibitors), such as simvastatin and atorvastatin, reduce cholesterol production by the liver, resulting in lower LDL cholesterol levels, increase HDL cholesterol and mildly reduce triglycerides. Treatment should be monitored by regular blood tests to check the lipid levels and ensure liver and muscle enzymes are normal, as statins sometimes cause abnormalities especially when prescribed in higher doses.
  • Fibrates, such as bezafibrate, may be added to reduce triglyceride production by the liver, lowering triglycerids and increasing HDL cholesterol. They may cause gastrointestinal side effects.
  • Ezetimibe may be added in high risk patients or if higher doses of statins are poorly tolerated. It reduces cholesterol absorption from the gut, lowering total and LDL cholesterol.
  • Nicotinic acid lowers cholesterol, LDL cholesterol and triglycerides, and increases HDL cholesterol. At therapeutic doses of at least one gram daily, it causes flushing. An analogue, acipimox, is better tolerated.
  • Cholestyramine and colestipol are rarely used as they are not as effective as the medications listed above and they are poorly tolerated.

Surgery or locally destructive modalities can be used to remove xanthomas that do not resolve spontaneously or with treatment of the underlying cause. Xanthoma disseminatum affecting vital organ functions may be treated by chemotherapy drugs or radiotherapy.

Treatments for xanthelasma include:

  • Topical trichloroacetic acid
  • Electrodesiccation
  • Laser vaporisation
  • Excision.
Trichloracetic acid treatment of xanthelasma

 

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