Maculopapular cutaneous mastocytosis (formally called urticaria pigmentosa)

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Maculopapular cutaneous mastocytosis (MPCM) is a condition where immune cells build up in the skin, producing red-brown spots or bumps. Learn how MPCM is diagnosed and treated.

Key points

Most cases of MPCM appear before the age of 2 and often disappear or improve greatly by puberty.
In most children, symptoms that happen during a flare-up are mild and easily managed at home. Very rarely, systemic symptoms can occur, such as flushing, diarrhea and vomiting, wheezing or anaphylaxis.
There is no cure for MPCM, but treatment with medications and avoiding triggers can help control symptoms.
See a health-care provider for MPCM if your child shows signs of a severe allergic reaction or develops many new spots.

Introduction

What is maculopapular cutaneous mastocytosis (MPCM)?

A baby with light brown spots all over their back

Our immune system contains different types of cells, including mast cells. Immune cells help the body heal after an injury and respond to possible allergens. MPCM is a condition where mast cells build up in large numbers in the skin, hair or nails and cause a rash.

Signs and symptoms

How does MPCM affect the body?

Closeup on a raised red spot on someone's skin

MPCM most commonly appears as red-brown spots or bumps and can affect any part of the body. The number of spots varies from child to child, from just a few to over a hundred.

Sometimes, these spots can be itchy. After vigorous rubbing, they can become red and swollen. This is a sign that the mast cells are activated. Your child’s health-care provider might describe the redness and swelling as a positive Darier’s sign.

The spots associated with MPCM can sometimes become fluid-filled blisters. Spots usually do not leave a scar, but they can linger for months to years.

MPCM is limited to the skin in most children. In rare cases, it can produce other symptoms, such as:

diarrhea
vomiting
flushing
wheezing
anaphylaxis (serious allergic reactions)

If your child has any of these unusual symptoms, seek medical attention urgently.

Causes, risk factors and prevalence

What causes MCPM?

MPCM is caused by the build-up of mast cells within the skin, which produces spots. When activated, mast cells can release mediators, or chemicals, which produce the characteristic symptoms described above.

Spread, phase, course of disease

What to expect with MPCM over time

Over half of MPCM cases appear in children aged under 2. New spots can continue to appear over the next few years.

MPCM is not harmful. It is usually limited to the skin, with a low risk of other organs being involved.

MPCM usually improves with time. It is not usually a permanent disease. About half of all cases resolve by puberty, and the other half improve greatly by then.

Diagnosis

How is MCPM diagnosed?

MPCM is easily diagnosed in clinic if a child under age 2 has red-brown spots and a positive Darier’s sign. When the diagnosis is more uncertain, your child’s health-care provider may perform a skin biopsy.

Once MPCM is diagnosed, a dermatologist (a skin specialist) will monitor your child’s skin.

Usually, your child will not need further testing. However, their health-care provider may consider doing a blood test or may refer your child to a hematologist (a blood specialist) if:

your child has many spots
the spots look unusual
any flare ups (redness and swelling) take longer to resolve than usual
your child has severe systemic complaints (symptoms that affect the whole body), such as severe vomiting, diarrhea or wheezing
the condition gets worse in later childhood, which is not the typical course

Treatment

How is MPCM treated?

Unfortunately, there is no cure for MPCM. However, most children affected by the disease improve by puberty. In the meantime, the symptoms of MPCM can be treated successfully with a range of approaches.

Avoiding triggers

Examples of common triggers include:

medications such as aspirin, NSAIDs (such as ibuprofen), opioids, some anesthetics and X-ray contrast dye
stimuli such as stress, heat and direct sunlight

Always tell your child’s health-care provider if your child has MPCM so they can avoid using or recommending anything that may trigger your child’s symptoms. They may recommend that your child wears a medic-alert bracelet so health-care providers are aware that your child has MPCM.

Medications

Antihistamines can help relieve the itchiness and other side effects of mast cell activation, such as redness and swelling.
Corticosteroid creams can relieve itching.
An epinephrine autoinjector (such as an EpiPen) can help treat severe allergic reactions. Your child should always carry one with them if they have a history of anaphylaxis.

Light therapy

Light therapy (PUVA) has been used successfully in some severe cases.

Complications

Complications of MCPM

In a very small number of cases, mast cells may build up in the liver, spleen or bone marrow. This is such a rare occurrence in children that regular screening is not recommended. Adults with MPCM can sometimes develop leukemia, but this is extremely rare in children.

When to seek medical attention

When to see a health-care provider for MPCM

Go to the nearest emergency room if your child shows any signs of a severe allergic reaction or difficulty breathing.
See your child’s dermatologist if your child develops many more or many different types of spots or if your child has new symptoms such as vomiting or diarrhea.

Resources

Further information

For more information on maculopapular cutaneous mastocytosis, visit Mastokids.org, a website to support children and families living with mastocytosis.

Last updated: July 29th 2026