What is urticaria pigmentosa?

Urticaria pigmentosa is a condition that makes your skin itch and causes discolored lesions (salmon-brown patches). You may develop a hive after stroking the affected area. It might happen due to an allergic reaction. This condition is more common in infants and children but may also happen in adults.

It is one of the signs that doctors look for when diagnosing a disorder known as mastocytosis. This disorder is characterized by mast cell accumulation, mostly in the skin, bone marrow, digestive system, spleen, liver, and lymphatic tissues.

It causes a  rash made up of reddish-brown spots that are flat or slightly raised. They may form hives when they are rubbed or scratched. Sometimes the spots will blister. There may be a few spots or many spots. The lesions usually are most prominent on the trunk but can occur on the scalp, face, and extremities.

Signs and symptoms of urticaria pigmentosa

In children, urticaria pigmentosa may have the following common signs:

  • Itchy, pink, or red swollen patches on the skin
  • Hives that may appear alone, in a group, or on a large area of the body
  • The hives that appear as a result of urticaria pigmentosa may go away in 24 hours in one area but may come back in a different area

When urticaria pigmentosa occurs to you as an adult for the first time, lesions may appear. They might be few or may appear in large numbers. The lesions may also be itchy and unsightly. This condition affects adults differently. This is because urticaria pigmentosa in adults appears long-term. You might experience other symptoms such as:

  • Flushing: A redness on the skin caused by an uncontrollable response of the nervous system leading to the widening of blood capillaries of the involved skin.
  • Low blood pressure: This is blood pressure that is so low that you get symptoms or signs because of the low flow of blood through the blood vessels.
  • Anaphylactic Shock: A widespread and very serious allergic reaction that requires emergency treatment.
  • Diarrhea: Passing loose stool.
  • Bleeding from the digestive system: You may notice this by seeing some blood on your stool.

If these systemic symptoms appear, they could be a sign of the presence of systemic mastocytosis. This is a form of mastocytosis that infiltrates mast cells in the skin.


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Causes of urticaria pigmentosa

Urticaria pigmentosa occurs where there are too many inflammatory cells (mast cells) in the skin. Mast cells are immune cells that help the skin fight off infections. They are responsible for making and releasing histamine, which makes nearby tissues to get swollen and inflamed.

There are a few things that can trigger the production of histamine and in turn cause skin symptoms. They include:

  • Rubbing the skin
  • Drinking hot liquids or eating spicy food
  • Exercise
  • Exposure to sunlight or cold
  • Medications such as aspirin or other NSAIDs, morphine, codeine, alcohol, x-ray dye, and some anesthesia medicines.

Diagnosis of urticaria pigmentosa

When you get to your doctor, they should begin the examination and order the right tests for the diagnosis of your condition. Your doctor may suspect you have urticaria pigmentosa when the skin patches are rubbed and they develop bumps (hives). This is called the darier sign.

Tests to check for this condition include:

  • Skin biopsy: Here, a part of the skin is taken and examined for a higher number of mast cells.
  • Urine histamine: Using this test, your doctor will determine whether you have an increased urinary histamine level.
  • Blood test: A blood test will help your doctor to check the blood count and levels of blood tryptase (an enzyme found in mast cell.

Treatment of urticaria pigmentosa

Your doctor will advise on the best form of treatment for you or your child. If there are no associated signs and symptoms, your doctor may not prescribe any medication.

However, if the condition shows symptoms, your doctor may recommend the following treatments:

  • Adrenaline: If you are an adult, you will be given at least an adrenaline auto-injector. This is because anaphylaxis may happen at any time. Children with Urticaria Pigmentosa don't need the auto-injector unless they have allergies or extensive skin lesions.
  • Oral sodium cromoglycate: This might be helpful in reducing bowel signs but it is not useful in other places.
  • Steroid creams: Your doctor may recommend potent steroid creams to reduce itching and improve the appearance of your skin.
  • Non-sedating antihistamines: This type of histamine works well for histamine-induced symptoms like flushing, itching, reddening, diarrhea, and wheezing.
  • Ultraviolet treatment: This treatment helps reduce the itching and improve skin appearance. 
  • Laser therapy: This method of treatment is used to improve certain areas with Urticaria pigmentosa.


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Medically Reviewed on 3/24/2021
Children's Mercy Kansas City: "Urticaria Pigmentosa mastocytosis."

Skin Support: "Urticaria Pigmentosa."

StatPearls: "Urticaria Pigmentosa."

University of Rochester Medical Centre: "Urticaria (Hives)."

University of Florida Health: "Urticaria Pigmentosa."

U.S. National Library of Medicine: "Urticaria Pigmentosa."