Xanthoma: Understanding Your Pathology Report

Section Editor: Bibianna Purgina, MD FRCPC
October 3, 2026

A xanthoma is a noncancerous collection of fat-filled immune cells. These cells, called foamy histiocytes, are histiocytes that have taken up fat, which makes them look bubbly or foamy under the microscope.

Most xanthomas develop in the skin, where they appear as yellow or orange bumps or patches. They can also form in tendons and, less often, in internal organs such as the stomach.

A xanthoma does not turn into cancer. Its main importance is what it can reveal. Some types signal high levels of cholesterol or other fats in the blood, which may need treatment in its own right.

This article explains the types of xanthoma, what they can mean for your health, and what the findings in your pathology report mean.

What causes a xanthoma?

A xanthoma forms when histiocytes collect fat from the surrounding tissue and accumulate in one place. This most often happens when too much cholesterol or triglycerides, another type of fat, is in the blood.

Several conditions can raise these fats, including inherited cholesterol disorders, poorly controlled diabetes, an underactive thyroid, and certain liver and kidney diseases. Some medications can also raise blood fats.

Not every xanthoma is linked to high blood fats. Some types occur in people with completely normal levels, and a few are linked to other conditions entirely.

What are the types of xanthoma?

The type depends on where the xanthoma develops and what it looks like. Each type points toward a different underlying cause:

Xanthelasma. Soft yellow patches on or around the eyelids. This is the most common type. About half of people with xanthelasma have high cholesterol, and the other half have normal levels.
Tendon xanthoma. Firm, slow-growing lumps in tendons, most often the Achilles tendon at the back of the ankle or the tendons on the back of the hand. These strongly suggest an inherited condition called familial hypercholesterolemia.
Tuberous xanthoma. Firm, painless yellow nodules, usually on the elbows, knees, or buttocks. These are linked to high cholesterol or triglycerides.
Eruptive xanthoma. Crops of small red-yellow bumps that appear suddenly, often on the buttocks, shoulders, or thighs. These are linked to very high triglyceride levels, often with poorly controlled diabetes.
Palmar xanthoma. Yellow streaks in the creases of the palms and fingers. These are linked to a specific inherited disorder of how the body handles fats.
Palmar xanthoma. Flat yellow patches on the skin, sometimes widespread. When they occur in a person with normal blood fats, they can be linked to an abnormal protein in the blood made by plasma cells.
Verruciform xanthoma. A wart-like bump, usually in the mouth or the genital area. This type is not linked to blood fats.

Xanthomas in the stomach and other organs

A xanthoma in the stomach is a small yellow spot, usually just a few millimeters across, found during an endoscopy. It is common and not linked to high blood fats.

These spots are more common in people with long-standing inflammation of the stomach lining, called chronic gastritis. They need no treatment. The importance of a stomach xanthoma is that it is a harmless explanation for a spot your doctor saw and sampled.

What are the symptoms of a xanthoma?

Most xanthomas cause no symptoms apart from their appearance. Skin xanthomas are usually painless, although eruptive xanthomas can be itchy or tender. Tendon xanthomas may cause discomfort in the tendon, particularly in the Achilles tendon.

How is the diagnosis made?

Many xanthomas are recognized by their appearance, especially xanthelasma. A pathology report is produced when a biopsy is taken, or the lesion is removed.

Under the microscope, a xanthoma is made of foamy histiocytes, large immune cells packed with small fat droplets. These cells may be accompanied by other immune cells. Older xanthomas, particularly in tendons, may also contain scarring (fibrosis), calcium deposits (calcification), or needle-shaped spaces left by cholesterol crystals (cholesterol clefts).

The pathology report confirms the lesion is a xanthoma and shows no evidence of another type of growth. The microscope cannot tell what caused the xanthoma. Blood tests and your medical history determine that.

Why does a xanthoma lead to blood tests?

Finding a xanthoma often leads to a blood test called a lipid panel, which measures cholesterol and triglycerides. High levels raise the risk of heart disease and stroke, and they can be treated.

Two types of xanthoma are particularly important:

Tendon xanthomas. These suggest familial hypercholesterolemia, an inherited condition that causes very high cholesterol from birth. Each child of an affected parent has a 50% chance of inheriting it, so family members are usually tested as well.
Eruptive xanthomas. These indicate very high triglyceride levels, which can cause inflammation of the pancreas, a serious condition. Prompt medical assessment is needed.

A plain xanthoma in someone with normal blood fats may also prompt blood tests for an abnormal protein. This protein can indicate a condition such as monoclonal gammopathy of undetermined significance.

What is the prognosis?

A xanthoma itself is noncancerous and does not spread. The outlook depends on the underlying cause, not the xanthoma.

When the cause is high blood fats, treating them can make some xanthomas shrink or disappear. Eruptive xanthomas often fade within weeks once triglycerides are controlled. Tendon xanthomas and xanthelasma tend to change more slowly, if at all.

What happens after the diagnosis?

Blood tests. Most people with a skin or tendon xanthoma should have their cholesterol and triglycerides checked.
Treating the underlying cause. When blood fats are high, doctors use diet, exercise, and cholesterol-lowering medication. Better control of diabetes or thyroid disease can also help.
Removing the xanthoma. A xanthoma can be removed for appearance or comfort, using surgery, laser treatment, or freezing. Xanthelasma often comes back after removal, especially if blood fats remain high.
Family testing. Relatives are usually tested if you are diagnosed with familial hypercholesterolemia.
No treatment. A stomach xanthoma needs no treatment or follow-up.

Questions to ask your doctor

Which type of xanthoma do I have?
Should I have my cholesterol and triglycerides checked?
Could I have an inherited cholesterol condition?
Should my family members be tested?
Will treating my blood fats make the xanthoma go away?
Can the xanthoma be removed, and is it likely to come back?