We were impressed with Dr. Michael Siegel’s "Sherlockian" approach to resolving this child’s perioral dermatitis in August JADA’s "Perioral Dermatitis" (JADA 2006;137[8]: 1121–2). Recreating the pattern of lesions in the extraoral path of the mouthwash was exemplary and, sadly, should have been done by one of the patient’s dermatologists. As illustrated here and in the medical literature, dermatologists are more likely to prescribe topical steroids and antimicrobials.
Allergic contact dermatitis is common in children. Recent estimates suggest that 20 percent of the pediatric population may be allergic to one or more contact allergens.1 Therefore, dentists are likely to care for patients with this condition.
However, diagnosing allergic contact dermatitis should be based on a thorough health history, detailed symptom evaluation and diagnostic patch testing.2 [Patch testing] requires applying standardized test allergens to the back for two days, removing them and then reading skin reactions over the next several days. Children are routinely and successfully patch-tested by physicians experienced in the technique.3
Dr. Siegel adroitly tackled the first two steps in the diagnostic path: history and symptom details. But without patch testing, the diagnosis of "contact hypersensitivity to cinnamon flavoring" is hardly "definitive." In fact, dermatologic patch-test guidelines emphasize the errors resulting from a diagnosis based solely on history and symptoms.2
In this case report, the culpable allergen remains undefined owing to the lack of diagnostic patch testing with specific chemical allergens. Other mouthwash ingredients—such as benzyl alcohol and colorings—could be involved in the skin reaction. In addition, the chemical constituents of cinnamon flavoring (cinnamic aldehyde, cinnamic acid, cinnamic alcohol, eugenol, cinnamein, etc.) vary by source and are found in other fragrances, flavorings and foods.4 Without specific patch testing, the allergen is unknown, and the child (or the parent) has a limited ability to avoid exposure.
Undiagnosed and misdiagnosed allergies can diminish a patient’s quality of life.5 In this case, the dermatitis pattern and suspect allergen were discovered by Dr. Siegel’s notable care. However, a definitive diagnosis should include diagnostic patch testing with specific chemical allergens, and we would advise greater collaboration between a patient’s dentist and physician to avoid the negative impact of an incomplete diagnosis.
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