What Is Urticaria Pigmentosa and How Is It Managed?

Written by Madeline Laguaite
Medically Reviewed by Zilpah Sheikh, MD on June 18, 2025
5 min read

Urticaria pigmentosa — also known as maculopapular cutaneous mastocytosis (MPCM) — is an itchy rash that shows up most often in children and young adults. The rash may look reddish-brown, gray, purplish, or tan, depending on your skin tone. It may turn into hives or blisters when you rub or scratch it. This reaction is called Darier’s sign.

Urticaria pigmentosa is a type of mastocytosis — a condition in which mast cells (a part of your immune system) build up too much in your skin, bones, intestines, or other organs. With urticaria pigmentosa, mast cells build up in your skin.

A change, or mutation, in your DNA causes urticaria pigmentosa. This change usually happens in the womb, but it’s not passed down from your parents. Doctors don’t know what causes this mutation.

The genetic mutation causes a buildup of mast cells (a part of your body’s immune system). They’re a type of white blood cell that’s created in your bone marrow. Mast cells are found throughout your body, especially the areas that interact with the outside world. This includes your skin, lungs, and intestines. When your mast cells detect germs, allergens, or other threats, they release a chemical compound called histamine to try to protect your body.

Urticaria pigmentosa is the most common form of mastocytosis in children. Mastocytosis is more likely to be lifelong in adults and can get worse over time. The most common form in adults is indolent systemic mastocytosis. With this type, you have a buildup of mast cells in your skin as well as other areas (usually the bone marrow).‌

Rarely, mastocytosis can turn into certain types of cancer. These include mast cell leukemia and mast cell sarcoma. In these forms of mastocytosis, too many mast cells build up in your organs. This usually happens in your bone marrow, bones, gut, or liver. These types of mastocytosis are serious and can worsen quickly.

More than 3 in 4 cases of urticaria pigmentosa start in children under 10, but the condition can affect older children and adults, too.

Is urticaria pigmentosa contagious?

Urticaria pigmentosa isn’t contagious. That means you can’t spread it to another person.

Urticaria pigmentosa triggers

Some things can make urticaria pigmentosa worse. Some medicines and other substances that can do this include:

Other triggers can include:

  • Exercise
  • Rubbing your skin with towels
  • Hot baths
  • Hot drinks
  • Sunlight
  • Exposure to cold
  • Spicy food

The most characteristic symptom of urticaria pigmentosa is a rash that shows up on the trunk, arms, and legs. This happens when the rash is rubbed, which causes it to release histamine, a response known as Darier’s sign. Then, the rash becomes itchy, swollen, and may even blister. The rash might look reddish brown on light skin. With darker skin, it might have a tan, brown, gray, or purple tone, or it may be the same color as your skin.

Some people may have the following symptoms:

  • Racing heartbeat
  • Diarrhea
  • Flushing (redness of the skin)
  • Wheezing
  • Fainting
  • Headache

The urticaria pigmentosa rash is so specific that it can usually be diagnosed without any other tests. If your doctor thinks your urticaria pigmentosa may be part of wider mastocytosis, you may need more testing, such as:

  • Blood count, which will give your doctor more information about the types and amounts of different cells in your blood
  • Serum tryptase, which tests for an enzyme that’s released from mast cells
  • Bone density scan, which shows how strong and thick your bones are
  • A bone marrow test to see if your bone marrow is healthy and making cells

As long as it only involves your skin, urticaria pigmentosa doesn’t usually need treatment. While there’s no cure, the following treatments may help ease symptoms in certain cases:

You should also avoid anything that triggers reactions and makes your symptoms worse.

Most of the time, urticaria pigmentosa doesn’t cause any lasting complications.

But in very rare cases, it can turn into system-wide (systemic) mastocytosis. People with mastocytosis are more likely to have a life-threatening allergic reaction called anaphylactic shock. Up to half of adults with urticaria pigmentosa may have a serious allergic reaction during their lifetime. This is less common in kids. 

Other possible complications of systemic mastocytosis include:

  • Osteoporosis, in which your bones become weak and soft
  • Cytopenia, in which your body doesn’t make as many cells as it should
  • Liver problems
  • Cancer (though it’s rare, people can get cancers involving mast cells)

Urticaria pigmentosa can’t be prevented. Most children will outgrow urticaria pigmentosa as they get older. There’s no treatment to prevent new spots from forming. The spots may fade eventually, but they usually last for years.

Urticaria pigmentosa is an itchy rash that can turn into hives or blisters when rubbed or scratched. It mostly affects kids, and most of them outgrow it over time. The condition doesn’t usually need treatment. But in rare cases, it could lead to mastocytosis that affects organs and tissues throughout your body.

Here are some commonly asked questions about urticaria pigmentosa.

What medications should be avoided with urticaria pigmentosa?

Drugs that trigger the release of body chemicals called histamines could make urticaria pigmentosa symptoms worse. They include:

  • Medications used for general anesthesia 
  • Codeine, morphine, and other opiates 
  • Quinine, which treats and prevents malaria
  • Nonsteroidal anti-inflammatories (NSAIDs), such as aspirin or ibuprofen
  • Scopolamine, which treats nausea caused by motion sickness or surgery 
  • Procaine, which dentists might use to numb your mouth
  • Polymyxin B, used for serious infections

Ask your doctor before using these medicines.

What is the new name for urticaria pigmentosa?

People with urticaria pigmentosa can have flat or raised rashes. Because of this, you may hear the condition called “maculopapular cutaneous mastocytosis” (“macule” means flat, and “papule” means raised).

Is urticaria pigmentosa a rare disease?

Yes, urticaria pigmentosa is a rare condition. Experts aren’t sure exactly how many people have this type of mastocytosis (a condition in which too many mast cells build up in your body). Researchers estimate that 1 in every 10,000-30,000 people has mastocytosis.

Which food is not allowed with urticaria?

Everyone’s different, and there’s no list of foods that all people with urticaria pigmentosa should avoid. But certain foods may worsen symptoms for some people. They include:

  • Spicy foods
  • Alcoholic drinks
  • Cheese
  • Lobster and crawfish
  • Hot drinks