What Is Urticaria Pigmentosa?
Urticaria pigmentosa (UP) is an allergy-mediated skin condition
that causes discolored lesions and itchy skin. The condition is characterized
by the presence of too many mast cells in the skin. Mast cells are part of your
immune system. Their job is to produce inflammation by releasing a substance
called histamine in response to germs and other invaders. In UP, there are too
many mast cells in your skin.
This disease is most commonly seen in infants and children, but
adults may be affected as well. The main symptom is dark-colored lesions on the
skin. The lesions may be very itchy and difficult not to scratch. When rubbed
or scratched, the lesions respond with a Darier’s sign. A Darier’s sign looks similar to
hives. It’s caused by the release of histamine from the mast cells.
In most children, UP goes away by puberty. Complications are
typically only seen in older children or adults. Rarely, UP may evolve
into systemic mastocytosis in
an adult. In systemic mastocytosis, mast cells can build up in other organs of
the body. In extremely rare cases, this may result in mast cell leukemia or
mast cell sarcoma, which are both forms of cancer.
Recognizing Urticaria Pigmentosa
The main symptom of UP is brownish lesions on the skin. Rubbing
the lesions releases histamines which produce intense itching along with
blisters or hives (Darier’s sign).
Symptoms of UP may include:
- pruritus (itching that varies in severity and
- flushing (redness of the skin)
- overpigmentation of lesions (very dark coloring
Adults or adolsecents are more likely to have uncommon symptoms.
- tachycardia (rapid heart rate)
- nausea or vomiting
Cause of Urticaria Pigmentosa
The exact cause of UP is unknown. There may be a genetic cause
for some cases (the child either inherits an abnormal gene from one of their
parents, or there is a gene mutation), while other cases appear for no reason
at all. The inherited form of UP is very rare, with only about 50
Doctors do know that when the lesions are rubbed, they release
histamines. Histamines are
chemicals that start an immune response. Ordinarily the immune system is activated
in response to germs or other invaders. In UP, there is no invader. The immune
response results in itchy lesions on the skin.
Diagnosis of Urticaria Pigmentosa
The diagnosis of UP is based on observation of the lesions.
Darier’s sign is a classic symptom that implies UP and most lesions look
similar in color. Lesions that appear different from others may be a sign of
Possible cancers may include:
- melanoma (the deadliest of skin cancers)
- basal cell carcinoma (uncontrolled growths or
lesions in the outer layer of skin)
- actinic keratosis (a precancerous scaly patch of
skin caused by years of sun exposure)
Your doctor will test any unusual looking lesions for cancer.
This will require a small skin sample for microscopic examination and testing.
A skin biopsy will be recommended for this purpose.
Treatment of Urticaria Pigmentosa
There are no cures for UP. Treatment focuses on easing symptoms
and controlling lesions. Your doctor will recommend a specific treatment based
on the number of lesions and your tolerance. For example, painless and
easy-to-apply treatments might be best for young children.
Treatment options include:
- antihistamines to relieve itching and flushing
of the skin
- topical corticosteroids (gel or cream with
- intralesional corticosteroids (injection with
anti-inflammatory steroid medications)
- hydrocolloid dressings (act like a bandage to
hold medication to the skin)
acetonide (a synthetic corticosteroid)
maleate (antihistamine used to control allergic reactions)
In adults, a form of light therapy called photochemotherapy using
ultraviolet radiation has proven to be an effective treatment.
In order to encourage recovery:
- do not rub the skin
- do not pick at blisters (no matter how tempting)
- do not scratch the lesions (this will only send
out more histamines creating a bigger reaction)
People with UP should avoid certain medications, including:
- opiates (morphine and codeine)
Alcohol intake should be limited or eliminated completely since
it can be a trigger for UP.
Complications of Urticaria Pigmentosa
Most cases of UP affect only the skin. Cases where UP affects
other organs are generally found in older children and adults.
Organs which may be affected by UP include:
Unfortunately, the treatment for UP can have some unintended side
effects. Side effects of prolonged treatment include:
- red skin syndrome (corticosteroid withdrawal)
- diabetes mellitus (glucose intolerance due to
chronic use of steroid therapy)
- insulin resistance (body grows immune to the
presence of insulin)
Outlook for Urticaria Pigmentosa
Most cases of UP appear in children. As they grow older, the majority
will outgrow the disease. Lesions generally fade as a child moves into
adulthood. Up to 25 percent do not outgrow the disease and retain lesions into
Preventing Urticaria Pigmentosa
There is no sure way to prevent UP. The inherited form is very
rare, and even when the child has the abnormal gene, they may not ever develop
However, you can prevent the disorder from getting worse. Try to
help your child keep from scratching or rubbing their irritated skin to prevent
the lesions from spreading:
- avoid hot baths to keep from drying out their
skin and making the itching worse
- bathing in lukewarm (or cool) Aveeno oil baths
have been shown to control itching
- avoid itchy, irritating clothing — try cotton or other light fabrics
- keep their fingernails short
- have them wear light cotton gloves to bed to
Your pediatrician may have more tips. Most cases of UP clear up
by the time the child is a teenager.