Urticaria,pressure.

Pressure urticaria (PU) is an uncommon form of physical urticaria. It may occur immediately or 4-6 hours after a pressure stimulus, and it lasts 8-72 hours. The hands, the feet, the trunk, the buttocks, the legs, and the face are the most common areas affected. Lesions can be induced by a variety of stimuli, including standing, walking, wearing tight clothes, or sitting on a hard surface.

The pathogenesis of PU is unknown. No allergen can usually be found. Mast cells are believed to play a role because injection of a compound 48/80, which causes depletion of mast cell mediators, prevents the induction of lesions in the injected area. Histamine levels are increased in lesional skin, and intracellular histamine levels are decreased in peripheral white blood cells. Despite these findings and the finding of increased stimulated histamine release, histamine is not likely to be the sole mediator in PU. Evidence supporting other mediators includes the relative unresponsiveness of conditions to antihistamine treatment. In the US PU is considered a rare entity, but some investigators have suggested that PU may be more common but not consistently recognized. PU is a chronic disease, with a mean duration of 9 years (range, 1-40 y). Depending on the severity of the disease and the associated symptoms, PU can be disabling, especially in patients who perform manual labor. The mean age at onset is in the early 30s (range, 5-63 y).

Signs and symptoms of PU initially appear 4-6 hours after a pressure stimulus; theypeak at 6 hours, and they remain for 8 hours to 3 days.

Lesions can occur on any cutaneous surface, and they may be associated with fever; malaise; fatigue; and, occasionally, chills, headache, and generalized arthralgias. The lesions may be pruritic, painful, or burning.

Affected areas can be refractory to the development of new lesions for 1-2 days.

In as many as 60% of individuals who are affected, PU coexists with chronic urticaria, immediate and/or delayed dermatographism, and/or angioedema.

Causes

Pressure stimuli

Standing, walking, or sitting on a hard surface,Using tools, such as a screwdriver or a hammer,Hand clapping,Carrying a handbag,Wearing tight-fitting clothes,Dental work,Kissing,Sexual intercourse,Tampon use.

Occasionally aggravated by heat, aspirin, or menstruation

Lab Studies

An elevated white blood cell count may be found with a CBC.

The erythrocyte sedimentation rate (ESR) may be elevated.

Thyroid microsomal antibodies may be present in cases associated with chronic urticaria.

Other Tests

Pressure challenge testing (dermographometer, suspended weight method) may be performed. Methods of applying measured amounts of pressure can be used to test for the development of PU.

The histologic features of the lesions are variable, ranging from dermal mononuclear cell infiltrates alone to combinations of mononuclear cells, eosinophils, and neutrophils in a perivascular and interstitial pattern in the dermis and subcutaneous fat. Degranulated mast cells may be noted. Early lesions are characterized by eosinophils and neutrophils, whereas the late lesions typically demonstrate eosinophils and lymphocytes.

Medical Care

Patients should avoid pressure stimuli, though this is not usually helpful inpatients with moderate-to-severe disease.

Antihistamines are helpful in controlling associated chronic urticaria.

Systemic corticosteroids and/or nonsteroidal anti-inflammatory drugs (NSAIDs) produce variable responses.

Consult a dermatologist for evaluation for other causes of urticaria.

Restrictions in activity depend on the severity of the disease.