Allergic contact dermatitis prevalence in patients with eczematous external otitis.

Eczematous external otitis, because of its basic allergic nature, tends to be chronic or recurrent. The purpose of our study was to investigate the association between allergic contact dermatitis and chronic eczematous external otitis. Sixty-six patients with eczematous external otitis and 48 healthy volunteers were included in this study. All the patients were tested with an epicutaneous patch test. In the study group, the average recurrent attack rate was 6.1+/-1.5 (between 4-9 times during the last year) in the patch test positive eczematous external otitis patients, and 4.9+/-1.3 (between 4-8 times during the last year) in the patch test negative patients (p = 0.002). The epicutaneous patch test was positive in 19 (28.8%) out of 66 cases with chronic eczematous external otitis, and in 3 (6.3%) out of 48 cases in the control group. The difference between the two groups was statistically significant (p = 0.003). The most common reactions were due to neomycin sulfate and potassium dichromate in this study. These results suggest that, in some cases eczematous external otitis may be considered as a form of delayed type hypersensitivity to allergen stimuli. Patients suffering from eczematous external otitis symptoms should be investigated for allergens.