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Background

The classification of Cholinergic Urticaria is a physical urticaria which means that it is the result of some kind of physical stimulus. The actual cause may be defined as sweating but it might be stated as heat.

Pathophysiology

Cholinergic Urticaria is usually included in studies of mast cell activity since in most cases it seems to critically involve the mast cells. Serum histamine is the principal mediator, which during experimentally induced exercise is introduced it rises in concentration. Eosinophil and neutrophil chemotactic factors are involved in treatment along with tryptase. The use of danazol results in improvement in the eruption and the alpha 1-antichymotrypsin levels decrease. Some have argued in favor of proteases as a cause of histamine being released as a result of these findings.

Even though the release of mast cells seems to be involved, there is less eosinophilic major basic protein present than in many other forms of urticaria. Researchers believe there is an allergic base involved as a result of several factors. An increase in the number of incidents of attacks in patient with atopic dermatitis is one of these factors, including a considerable sensitivity in some patients who suffer from anaphylactic and anaphylactoid reactions and some patients showing immediate reactivity. In one report there are almost immediately a sensitivity to sweat with passive transfer. With respect to positive passive transfer, not all investigators have reported the same results. An increase in histamine levels can often be detected after five minutes of exercise and it reaches a peak of 25 ng/ml by thirty minutes.

During treadmill exercise the skin tends to produce a sensation of generalized warmth which is then usually followed by pruritus, erythema, urticaria, and brief respiratory tract symptoms such as shortness of breath, wheezing or both.

Frequency

The number of occurrences of cholinergic urticaria in the United States is varied. In researching Moore, Robinson and Warin discovered that approximately 0.2 percent of patients in an outpatient dermatology clinic had it, but it is shown to be more common in many published reports. In person with atopic conditions there are more occurrences such as those with asthma, rhinitis and atopic eczema but this is not exclusive information. The disease also have a rare familial form.

Sex/Age

There is no discrimination between men and women when it comes to cholinergic urticaria, although men appear to have it more widespread. The age of ten to thirty years are when the condition usually manifests itself, but the ages of sixteen to twenty-two is the average onset age. Most people have the condition continue for many years, retaining it into middle age and longer. The average length of time for twenty-two people in one study was for seven and a half years, but seven of the patients retained the condition for thirty years during follow-up studies.

History

After just a few minutes of sweating the lesions appear quickly and may last anywhere from a half hour to an hour with eighty minutes being the mean duration. Many patients choose to change their activity patterns since the symptoms are severe enough to avoid bringing on attacks.

Any activity that results in sweating can cause people to suffer an attack not just exercise even though it is seen as the most widespread trigger, it can even be caused by a simple change in the temperature of the room or outdoors.

Some people possibly only react when exposed to heat or exercise that generates heat when they are unacclimatized to the heat if they only have attacks during the winter.

Physical

The onset of small wheals with large flares surrounding them is usually preceded by itching, warmth, tingling, irritation or burning. Anyplace on the body but the palms and soles may get the lesions. In some cases the only visible part is the flares. Symptoms such as fainting, abdominal pain, diarrhea, salivation and headaches may be found in patients who are affected more severely. Researchers believe there is one kind of cholinergic uticaria that shows persistent and individual macules which only appear for a short time in one spot and continually at other spots. After stroking the skin of patient with cholinergic uticaria a localized distribution of typical tiny wheals is noticed. A cold-induced uticaria may present itself in the form of a limited area.

Causes

The formation of lesions in areas that were previously unaffected is caused by exercise and hot baths which irritate pruritus. Some reports have shown that patients with cholinergic urticaria have chronic urticaria but with a different morphology. Similar lesions appear with other urticarias including aquagenic urticaria, which appears with the presence of either hot or cold water.

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