Sanitary napkin contact dermatitis of the vulva: location-dependent differences in skin surface conditions may play a role in negative patch test results

Abstract

I herein report six Japanese female patients with sanitary napkin contact dermatitis of the vulva. This condition may not be uncommon, although only a few reports have been published in Europe and the USA and none from Asia. Routine patch test with a saline-soaked fragment of their sanitary napkins conducted on the flexor surface of the upper arm gave negative results in all the patients, although pruritic dermatitis was clinically reproducible, developing in a delayed fashion, 2-4 days after the use of any brands of sanitary napkin. Moreover, this dermatitis could be avoided by using a tampon together with wearing cotton shorts. These observations suggest that it is a kind of irritant dermatitis that is induced by the wet local conditions as well as by friction caused by wearing a sanitary napkin rather than that due to sanitary napkin components. Resistance of the skin against external irritant stimuli is variable among different body sites and the genital skin, which is covered by thin stratum corneum, is thought to have low resistance against various external irritating and mechanical stimuli induced by wearing a sanitary napkin. Moreover, it is reasonable to presume that the proliferation of the resident microorganisms of the genital skin that takes place under the wet conditions produced by the use of the napkin also plays a role in the induction of such a unique contact dermatitis. Unfortunately, the commonly employed patch testing method performed on the skin of the upper limb or back cannot simulate the local situation occurring on the vulva under the sanitary napkin. We are urgently in need of a modification in patch testing method that is suited to reproduce similar dermatitis in other body locations.