Summary about Disease
Urticaria Pigmentosa (UP) is the most common form of cutaneous mastocytosis, a rare disorder characterized by an abnormal accumulation of mast cells in the skin. These mast cells release histamine and other mediators, leading to various symptoms. While primarily affecting the skin, it can sometimes involve other organs. The severity varies greatly between individuals, ranging from mild skin irritation to more systemic manifestations.
Symptoms
The primary symptom is the presence of reddish-brown macules or papules on the skin, often more prominent on the trunk and limbs. Rubbing or scratching these lesions (Darier's sign) causes them to swell and itch (wheal and flare). Other symptoms can include:
Itching (pruritus)
Flushing
Blisters (especially in infants)
Headaches
Abdominal pain
Nausea and vomiting
Diarrhea
Fatigue
Bone pain
In severe cases, anaphylaxis (rare)
Causes
UP is caused by a genetic mutation in the KIT gene, specifically the D816V mutation in most adult cases. This mutation leads to the uncontrolled proliferation and accumulation of mast cells in the skin and sometimes other organs. The exact trigger for the initial mutation is often unknown.
Medicine Used
4. Medicine used Treatment focuses on managing symptoms. Common medications include:
Antihistamines: To reduce itching and flushing. H1 and H2 blockers are often used in combination.
Topical corticosteroids: To reduce inflammation and itching on the skin lesions.
Mast cell stabilizers (e.g., cromolyn sodium): Can help prevent mast cell degranulation and release of mediators. Available as topical creams or oral medication.
Leukotriene inhibitors: May help reduce inflammation and symptoms.
Epinephrine (EpiPen): For severe allergic reactions (anaphylaxis).
Phototherapy (PUVA or UVB): May be used to reduce the number of mast cells in the skin.
Omalizumab: In some cases, for severe symptoms refractory to other treatments. In very rare and severe cases, particularly with systemic involvement, medications such as interferon-alpha or cladribine may be considered, but these are generally reserved for advanced disease.
Is Communicable
No, Urticaria Pigmentosa is not communicable. It is not contagious and cannot be spread from person to person. It is a genetic condition, not an infectious disease.
Precautions
Individuals with UP should take precautions to minimize mast cell activation. This includes:
Avoiding triggers: These may include certain foods, medications (NSAIDs, opioids), insect stings, alcohol, stress, temperature extremes, and vigorous rubbing of the skin.
Wearing protective clothing: To minimize skin irritation.
Carrying an epinephrine auto-injector (EpiPen): If at risk for anaphylaxis.
Informing medical professionals: About the condition before any medical procedures or surgeries.
Avoiding certain medications: That are known to trigger mast cell degranulation, if possible.
Using fragrance-free and hypoallergenic products: For skin care.
How long does an outbreak last?
The duration of an outbreak varies. Individual wheals and flares (Darier's sign) typically resolve within minutes to hours. However, the underlying lesions of UP are chronic, and symptoms can persist for years or even a lifetime. The frequency and severity of outbreaks fluctuate depending on triggers and individual factors.
How is it diagnosed?
Diagnosis usually involves:
Physical examination: Evaluating the characteristic skin lesions.
Darier's sign: Rubbing a lesion to see if it swells and itches.
Skin biopsy: A sample of the affected skin is examined under a microscope to confirm the presence of increased mast cells.
Bone marrow biopsy: May be performed to assess for systemic involvement, particularly in adults.
Tryptase level: A blood test to measure the level of tryptase, a mast cell mediator. Elevated levels can support the diagnosis.
KIT mutation testing: Genetic testing to identify the D816V mutation.
Timeline of Symptoms
9. Timeline of symptoms
Infancy/Childhood: UP often presents in infancy or early childhood, with the appearance of skin lesions. Blistering may be more common in infants. Symptoms may improve or even resolve during puberty in some children.
Adulthood: UP may persist from childhood or develop in adulthood. Symptoms are typically chronic and fluctuating, with periods of exacerbation and remission. Systemic involvement is more common in adults.
Important Considerations
The severity of UP varies greatly between individuals.
While most cases are limited to the skin, systemic involvement can occur, especially in adults.
Anaphylaxis is a potential, though rare, complication.
Patients should be educated about potential triggers and how to avoid them.
Long-term follow-up with a dermatologist or allergist/immunologist is recommended.
There is a small risk of progression to systemic mastocytosis, especially in adults.
Genetic counseling may be considered for families with a history of mastocytosis.