ORLANDO – Acute urticaria in children is most often caused by infection, food, or medication, and a detailed history is imperative for improving the likelihood of identifying the culprit, according to Dr. Adam Friedman.
Mycoplasma is a particularly common infectious cause in children, but adenovirus, enterovirus, rotavirus, respiratory syncytial virus, Epstein-Barr virus, and cytomegalovirus also have been implicated in urticaria cases, Dr. Friedman, director of dermatologic research at the Albert Einstein College of Medicine, New York, said at the Orlando Dermatology Aesthetic and Clinical Conference.
Dr. Adam Friedman
With respect to foods, ask about intake of milk, eggs, peanuts, wheat, and soy. When it comes to prescription medications, antibiotics are an especially common cause.
“Nonsteroidal anti-inflammatory drugs are also a very important one. If you have a patient with a history of urticaria or a pediatric patient who has a history of urticaria of the mucosa, definitely educate the parents not to give them NSAIDs,” Dr. Friedman said.
Nonimmunologic direct mast cell activation also can be a source of acute urticaria, resulting from exposure to numerous products. These include, but are not limited to, polymyxin B, radiocontrast media, opiates, muscle relaxants, salicylates, and NSAIDs, all of which can “potentially induce urticaria in almost anyone,” he said.
Identifying the cause is more likely in acute case than in chronic cases, for which the etiology is unknown about 70% of time. Regardless, the good news is that about two-thirds of cases are self-limiting; it’s the other third that poses the greatest challenge, he said.
The best bet for nailing down a diagnosis and identifying the cause is an extensive history and physical evaluation.
“Ask a million and one questions to really get to the root of it. In some cases, chronic urticaria is really a diagnosis of exclusion,” he said.
Asking the patient to keep a diary to help identify any unusual exposures just prior to the episode, and having the patient or parent take pictures of the skin are shortcuts that can help.
Extensive laboratory testing is rarely helpful, but certain tests may be warranted. New European guidelines call for erythrocyte sedimentation rate/C-reactive protein and blood differential testing for chronic spontaneous urticaria, but others – like liver function tests, hepatitis B, antinuclear antibody, stool, urinalysis, thyroid function, and antithyroid antibodies – should be directed by the history. A complement panel may be useful in cases involving angioedema, and allergy skin testing may be warranted if a specific trigger can be implicated, but “don’t just order for the sake of ordering,” he said.
Biopsies are not typically useful except in suspected neutrophilic urticaria, which may indicate an association with autoimmune disease, as well as offer some insight into whether dapsone treatment would be helpful over other third-line therapies. Persistent cases of urticaria (lasting over 24-48 hours in one location) may suggest urticarial vasculitis, which would warrant a biopsy.
The therapeutic approach to urticaria involves educating patients about avoiding triggers and identifying and addressing underlying conditions, and using medications that address the pathophysiology of the disease (mast cells, histamine, etc).
In children, the guidelines are generally similar to those in adults, but there is a real push to avoid systemic steroids, Dr. Friedman said, noting that the only time he uses systemic steroids is as a bridge to get to the point where other therapies are beginning to take effect.
Other key concepts for managing urticaria in children, as published in 2013 (Acta. Derm. Venereol. 2013;93:500-8), include using second-generation histamine1 antihistamines for symptom relief, avoiding first-generation H1 antihistamines (due mainly to sedation), and using other therapeutic interventions only after carefully weighing risks and benefits, as evidence in children is lacking.
Nonsedating antihistamines are preferable, as sending kids to school on sedating medications can impact learning as well as social interaction, ultimately resulting in developmental delay.
Keep in mind that standard doses of such medications often are inadequate, and it is acceptable to work up to four times the dose, even in children, he said.
Triple-drug therapy, including H1 and H2 antagonists plus leukotriene blockers may be necessary.
“This is a very complicated and still important disease. The key is history – sometimes – and climbing the therapeutic ladder. These patients are really uncomfortable, and they will love you if you get this disease under control,” Dr. Friedman said.
One thing that might provide some comfort to the patients and their parents is the fact that urticaria in children does seem to have a point of remission. Parents often fear that their children will be plagued with urticaria for life, but a recent study of 92 patients showed that the remission rates at 1, 3, and 5 years were 18.5%, 54%, and 67.7% (J. Am. Acad. Dermatol. 2014;71:663-8).