[Nail polish allergy. An important differential diagnosis in contact dermatitis].
HISTORY AND CLINICAL FINDINGS: Case 1. A 34-year-old woman presented with a recurrent, itching and erythematous plaque on her right cheek. Case 2. A 27-year-old woman reported itching erythema on her fingertips from time to time recently. Inspection revealed dyshidrosiform blisters. Both patients had been using nail varnish and varnish remover. Case 3. A 49-year-old woman had, for about 5 years, repeatedly experienced itching erythema at the perionychium of several fingers on which she had placed artificial nails. Marked oedema and erythema was noted. INVESTIGATION: Extensive epicutaneous tests were performed on these patients. They showed sensitisation against important allergens in nail varnish (toluolsulphonamide-formaldehyde resin), nail varnish remover (benzophenone-2) and artificial nails (ethylacrylate), respectively. The three patients also showed type IV sensitisation against other substances. DIAGNOSIS, TREATMENT AND COURSE: Epicutaneous tests documented type IV allergies to important constituents of nail varnish, nail varnish remover and artificial nails. Symptoms and skin changes disappeared when these three items were no longer used. CONCLUSION: Allergies against nail varnish and its remover and against artificial nails should be included in the differential diagnosis of skin allergies, even when patients have additional type IV sensitizations against common allergens. As the causative allergen can be easily avoided, knowledge of the particular problems associated with these allergies is of a great practical significance.