Pressure-induced bumps and erythema

CASE #2: Dermatographism

Urticaria that results from the pressure of using a dull object to stroke the skin is called “dermatographism,” which literally means the ability to write on the skin. Also referred to as dermatographic urticaria or dermographism, the condition is seen in 4%–5% of the population and is one of the most common types of urticaria.

The classification of urticaria is often based on the various mechanisms that can elicit clinical disease. The major subtypes are spontaneous urticaria, physical urticaria, and contact urticaria. Spontaneous urticaria is usually further classified according to whether wheals occur repeatedly for less than six weeks (acute) or more than six weeks (chronic). Dermatographism is the most common type of physical urticaria. Other types include delayed pressure, cold contact, heat contact, solar, and vibratory. By definition, urticaria is characterized by the rapid appearance of itchy wheals that have central swelling of variable size surrounded by a reflex erythema. Such lesions are self-limiting and fleeting in nature, with a duration up to 24 hours.

People with dermatographism are sensitive to touch, scratching, and pressure. The skin develops a raised red and itchy rash within minutes of being stroked, and the rash recedes within an hour without any treatment. Dermatographism can be caused by stress, tight or abrasive clothing, watches, backpacks, glasses, energetic kissing, heat, cold, or anything that causes physical stress to the skin or the patient. While dermatographism is often considered idiopathic in origin, a number of triggering factors have been reported, including bacterial infection, scabies, liver disease, bee and wasp stings, and various medications. In many cases, dermatographism is merely a minor annoyance, but in some rare cases, symptoms are severe enough to impact a patient’s life.

Many clinicians believe that the tedious search for the underlying cause of any type of urticaria is usually fruitless. Even when the cause is found, appropriate management of the disorder is not necessarily followed by complete resolution of symptoms. The medical literature suggests that extensive screening investigations add little to the detection of underlying disorders. Of note, a fairly recent review on the topic of urticaria in a major dermatologic journal contained only one paragraph on investigations for urticaria.¹ Not surprisingly, few clinicians engage in energetic or enthusiastic pursuit of remedial measures for these patients.

Despite this lack of interest on the part of clinicians, urticaria can have a great impact on patients’ quality of life. While some find the condition to be merely a minor annoyance, others suffer considerable energy loss, sleep disturbance, and emotional upset. Urticarial patients can experience greater limitation because of  physical and emotional problems than patients suffering with respiratory allergies or vitiligo.

When evaluating a patient with urticaria, I recommend obtaining a detailed history of the circumstances surrounding the onset of the eruption in hopes of determining possible etiologic triggers. This history includes a detailed review of all recently administered medications, herbals agents, or supplements; food exposure via ingestion, inhalation, or contact; allergen exposure by inhalation; and occupational exposure to allergens or irritants. Ask about physical triggers, such as cold, exercise, heat, sweating, sun, or pressure. Investigate the possibility of recent insect sting or infectious processes, including possible tooth pain, respiratory virus, and viral hepatitis. Make sure the review of systems includes such systemic diseases as autoimmune, connective-tissue, and lymphoproliferative disorders.

The value of any laboratory workup for urticaria is also disputed in the literature. In my practice, a laboratory screen for underlying disease is a routine part of the first visit. Testing includes a complete blood count, urinalysis, electrolyte determination, and assessment of liver and kidney function.

The ideal treatment for any type of urticaria is the identification and avoidance of the specific cause, which can lead to improvement both of physical symptoms and patients’ quality of life. Quite often, no specific triggering factors can be determined from history, physical examination, and laboratory investigations. Pharmacologic treatment is palliative at best. If patients with dermatographism are not bothered by the condition, no treatment is needed. However, in most cases of urticaria, a majority of clinicians attempt to provide some symptomatic relief by instituting an H1 antihistamine with the possible addition nonsedating or low-sedating antihistamines for daytime use. What additional treatment is undertaken varies widely from clinician to clinician.

Besides avoidance or elimination of possible eliciting factors, the basic tenets of clinical management of urticaria include inhibition of mast-cell release and therapy aimed at target tissues of mast-cell mediators. Because the etiology of urticaria is often unclear, I add an additional approach, namely trial and error of therapies directed at possible latent infections, as well as having a liberal view of potential causes that can be eliminated. Consequently, unless history directs me otherwise, I place my patients on a three-step process in which treatments are tried and possible environmental, drug, or dietary factors are eliminated. Included in this array of trial-and-error therapies are a course of antibiotics, dietary manipulation, anti-inflammatory drugs (i.e., mesalamine [Asacol]), leukotriene receptor antagonists, ivermectin, and antipinworm therapy. The full array of instructional sheets and dietary elimination diets I use is available online.²

In the patient described here, dietary elimination of penicillin proved curative. This diet is based on the fact that milk products are contaminated by cows treated with penicillin. Thus, milk and all dairy products are to be avoided. Additionally, cow’s milk contains more than 25 different molecules, including casein and whey, that also have the potential of eliciting an allergic reaction. The specific foods that need to be avoided in such a diet are listed in the previously noted article. Although two-thirds of patients attribute urticaria to food, medical experts have divergent views, with reports of successful dietary maneuvers ranging from 0% to 92%. In one particular study, 57% of patients experienced some improvement by elimination of hidden sources of penicillin.³

Dr. Burkhart is clinical professor of dermatology at the University of Toledo College of Medicine and clinical assistant professor of dermatology at Ohio University College of Osteopathic Medicine in Athens, Ohio. He has no relationships to disclose relating to the content of this article.

References

1. Grattan CE, Sabroe RA, Greaves MW. Chronic urticaria. J Am Acad Dermatol. 2002;46:645-657.

2. Burkhart CG. Patient-oriented treatment for urticaria: a three-step approach with informational/instructional sheets. The Open Dermatology Journal.

3. Legrain V, Taieb A, Sage T, Maleville J. Urticaria in infants: a study in forty patients. Ped Dermatol. 1990;7:101-107.

From the February 01, 2010 Issue of Clinical Advisor