Causes, incidence, and risk factors
Urticaria pigmentosa occurs in areas where there are too many inflammatory cells (mast cells) in the skin.
Urticaria pigmentosa is most common in children. It can also occur in adults.
The main symptom is brownish patches on skin. Rubbing the skin sore causes a hive-like bump. Younger children may develop a blister that is filled with fluid if the bump is scratched.
The face may also get red quickly (flushed).
In severe cases, the following symptoms may occur:
Signs and tests
- Skin biopsy to look for a higher number of mast cells
- Urine histamine
- Blood tests for blood cell counts and blood tryptase levels
Antihistamines medicines can help relieve symptoms such as itching and flushing. Talk to your health care provider about which type of antihistamine to use.
The health care provider may prescribe other kinds of medicines symptoms from severe and unusual forms of urticaria pigmentosa.
Urticaria pigmentosa goes away by puberty in about half of the affected children. Symptoms usually get better in others as they grow into adulthood.
In adults, urticaria pigmentosa systemic mastocytosis. This is a serious condition that can affect the bones, brain and nerves, and digestive system.
The main problems are discomfort from itching, and concern about the appearance of the spots. Other problems such as diarrhea and fainting are rare.
Certain medicines may trigger flares of urticaria pigmentosa. Discuss these with your doctor.
Bee stings may also cause a bad allergic reaction in people with urticaria pigmentosa. Ask your doctor if you should carry an injectable epinephrine kit (such as EpiPen or Twinject) to use if you get a bee sting.
Calling your health care provider
Call your health care provider if you notice symptoms of urticaria pigmentosa.
Habif TP. Urticaria and angioedema. In: Habif TP, ed. Clinical Dermatology. 5th ed. St. Louis, Mo: Mosby Elsevier; 2009:chap 6.
Tharp MD. Mastocytosis. In: Bolognia JL, Jorizzo JL, Schaffer JV, et al, eds.Dermatology. 3rd ed. Philadelphia, Pa: Mosby Elsevier; 2012:chap 118.