Delayed pressure urticaria
What is pressure urticaria?
Pressure urticaria is characterised by the appearance of weals after pressure to the skin. Pressure urticaria may occur immediately after a pressure stimulus or more commonly, in delayed pressure urticaria, after a delay of 4-6 hours.
Lesions can be induced by a variety of stimuli including standing, walking, wearing tight clothes or sitting on a hard surface. The condition can occasionally be aggravated by heat, aspirin or menstruation.
Pressure urticaria is uncommon but probably not rare. It is a chronic disease with a mean duration of 9 years. The peak age of onset is in the 20's and 30's.
What are the symptoms of pressure urticaria?
The weal in pressure urticaria consists of redness and swelling of the skin and subcutaneous tissues. Lesions may last for 8-72 hours.
The hands, feet, trunk, buttocks, legs and face are most commonly affected.
Weals may be accompanied by fever, malaise, fatigue, and occasionally chills, headache and general joint aches.
Affected areas my be resistant to development of new lesions for 1-2 days.
Pressure urticaria has a significant adverse impact on the quality of life of patients, with important limitations in everyday activities such as prolonged walking or standing. It can be disabling in patients who perform manual labour.
What is the cause of delayed pressure urticaria?
The cause of pressure urticaria is unclear but it is likely to be an autoimmune disease. Cells called mast cells play an important part in the process. Mast cells are tissue cells that contain chemicals, including histamine, which provoke wealing.
In delayed pressure urticaria a standardised pressure stimulus will induce a delayed weal, which is often painful. In immediate pressure urticaria a weal will appear within minutes of the stimulus.
A blood count may show an increased white cell count and ESR, but it is often normal.
The results of treatment of pressure urticaria are relatively disappointing.
- Reduce pressure stimuli as far as practicable.
- Antihistamines help control associated chronic urticaria but rarely reduce pressure urticaria.
- The ultrapotent topical corticosteroid clobetasol propionate may reduce inflammation. Skin thinning can result from regular use. Milder topical steroids are not of benefit.
- Systemic corticosteroids produce variable responses and long-term use is associated with many potential adverse side effects.
- Other possible therapies include nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine, dapsone, sulfasalazine and montelukast.
- Ciclosporin and intravenous gamma globulin have been used in a small number of patients with severe and refractory disease.