Urticaria Pigmentosa

Definition

Urticaria Pigmentosa is the most common form of cutaneous mastocytosis. Urticaria pigmentosa is a rather uncommon disease that affects the skin.

It is an uncommon rash which usually affects the arms, necks, legs and trunks of children and young adults. The rashes are made up of reddish brown spots that turn into hives when they are rubbed or scratched. When the disease presents after the age of five it is more difficult to treat and may become chronic. In the most severe of cases urticaria pigmentosa can spread to the internal organs and require more invasive procedures.

Causes

The exact cause of urticaria pigmentosa is not fully understood. Some cases occur for no apparent reason, while others are thought to be inherited as an autosomal dominant genetic trait. However, not all children with the defective gene for urticaria pigmentosa will exhibit all of the characteristics of the gene (reduced penetrance). The spots in urticaria pigmentosa contain a large number of mast cells (cells are the bodies building blocks). Mast cells are immune cells (cells that fight infection) that live in the skin. Mast cells make a substance called histamine. Histamine causes hives, itching, and flushing.

Symptoms

The common symptoms are :-

• Appearance of brownish lesions on skin
• Fainting
• Blister formation over lesion when it is rubbed
• Facial flushing
• Diarrhea
• Headache
• Welt or hive formation when lesions are rubbed or scratched

Treatment

It may relieve some of the histamine-induced symptoms such as itching and flushing. Discuss the choice of antihistamine with your child's health care provider. With more severe and unusual forms of urticaria pigmentosa, systemic symptoms may need to be controlled with other medications.

There is no satisfactory treatment for urticaria pigmentosa. Patients with urticaria pigmentosa should avoid aspirin, codeine, opiates, procaine, alcohol. polymyxin B, hot baths, and vigorous rubbing after bathing and showering. These can release histamine which can cause itching, flushing and hives. Antihistamines such as Benadryl can help control itching, hives, and flushing. Antihistamines may relieve some of the histamine-induced symptoms such as itching and flushing.

No specific tests are required as the appearance of this condition is generally characteristic. At times a skin biopsy is necessary for confirming the diagnosis. One must avoid exercise or heat as it can aggravate the symptoms.