On the significance of the trichophytin reactivity in atopic dermatitis.

Patients with pure atopic dermatitis with and without tinea infection were investigated and compared with patients with long-lasting tinea infections and with controls, for presence of intracutaneous reactivity to trichoptin, Penicillium, Cladosporium and Alternaria antigens. RAST to Penicillium and Cladosporium was also performed. The results showed a lack of delayed reactivity, but an immediate reactivity to trichophytin in 50%/40% of atopic patients with/without tinea infection. Non-atopics infected with tinea showed 66% immediate and 33% delayed response to trichophytin. The reactivities in atopic dermatitis (but not in the non-atopic group) went general parallel with mould reactions tested intracutaneously or by RAST. It is assumed that a positive trichophytin reaction in atopic dermatitis does not necessarily mean sensitisation to dermatophytes, but is primarily the sign of a cross sensitivity to moulds.