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| Medical Education Section |
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Diagnosis: Urticaria
Discussion:
Urticaria, also known as hives, is a common cutaneous condition that results in very pruritic raised wheals in the skin. These wheals can assume plaque-like, papular, or annular/polycyclic forms. As in the case with this patient, some of the configurations can be striking and bizarre in appearance. The hallmark of urticaria is that the lesions will change over time; that is, even over a few hours, the lesions will migrate and change. I find it quite useful when I am trying to discover whether a patient has an urticarial reaction to ask them if I looked at the lesions in three hours would they appear the same or would they move? This almost always gives me the answer that I am looking for. The other clue in the diagnosis of urticaria is that it tends to be a very dermal process; that is, the surface of the skin is not involved. You should not see any breaks in the skin or scale.
The exact mechanism of urticaria is very poorly understood. In fact, in only 10% of cases of urticaria can we actually determine the cause. In those 10% of cases, I refer to the etiology as the I, such as inhalation of fragrances and fumes; ingestion of fresh fruit, dried fruit, and anti-inflammatories such as aspirin; injections, such as radiopaque dyes used in radiology; and infections. Oftentimes even a subclinical infection or mild sinus infection can trigger hives. The final I is idiopathic and that, as mentioned, occurs 90% of the time. In certain persistent or chronic cases, it might be helpful for patients to keep a journal indicating the places they have been, the events they have participated in, and the foods they have eaten. Every once in a while, this can have a rich reward. In fact, I can recall two patients who did this. One recounted that every time after she visited her aunt, she had an urticarial episode. In looking back, she realized this started occurring shortly after her aunt had new indoor paint throughout the house. The very mild fumes were causing urticarial breakout. I also had another patient who discovered in keeping a journal that he would break out, usually have an urticarial reaction on Sunday evenings. He was a hobbyist and enjoyed making ships in a bottle. This involved some very special tools and special glue. He discovered after he started using a new fragrant glue, his hives started coming. In both cases, when she stopped visiting her aunt (at her aunts house) and when he stopped using that specific type of glue, their hives resolved.
With urticaria, there tend to be two courses, a short acute variant that usually resolves in one to four weeks and then the more chronic form. In my experience, about two-thirds of the cases are the acute form and one-third of the cases are chronic. By conventional definition, chronic urticaria is any hives that last persistently more than three months.
My approach to treating hives is very simple. If it is extremely uncomfortable and interfering with an impending social event, I will certainly use oral prednisone at the dosage of 20 to 40 mg every morning for one to two weeks. It works well and does not need to be tapered off. This will only address short-term issues. I really like to use Claritin 10 mg tablets twice daily for one month. I tell patients it works very well and is nonsedating and to take it whether the hives are present or not and at the end of the month do a trial cessation to see if the hives stay away. In the majority of cases they do, but if they do not, repeat the Claritin for another month. Also, if there is any question of angioedema, I prescribe patients an EpiPen, have the pharmacist instruct them how to use it, and refer them to their primary care for additional workup regarding C1 esterase inhibitor activity. In this particular case, the child was given Claritin RediTabs daily for one month. At the end of the month, when she stopped taking the RediTabs, the hives remained away as mysteriously as they appeared. If the hives appeared again, the parents were instructed to restart the RediTabs and keep a journal. There are also a variety of urticarial sub-types, for additional information, please see the references below.
To read CME article on urticaria
Urticaria and Angioedema
To view other "Crutchield Dermatology Clinical Cases of the Month" in our archives please click here
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