[Arthroderma onychocola plus Arthroderma quadrifidum on atopic eczema : An exceptional constellation that warrants interpretation].

BACKGROUND

Occasionally, tinea is a differential diagnostic option in lesions of nummular atopic eczema. Mycological diagnostics can yield quite unexpected results.

OBJECTIVES

Evaluation of the detection of rare geophilic dermatophytes on atopic eczema, using mycological data and its clinical interpretation.

METHODS

Detailed conventional and genetic mycological work-up of scales collected from atopic eczema; correlation of the findings with the clinical context and the pertinent literature.

RESULTS

On a lesion of nummular atopic dermatitis two rare geophilic dermatophytes were detected synchronously: Arthroderma (A.) onychocola and A. quadrifidum. This was only the third isolation of A. onychocola ever and the first one on glabrous skin and in Germany. The strain grew on human stratum corneum and perforated hair. A. quadrifidum did not show unusual features. No pathogenetic relevance of this twofold colonization was noted regarding the atopic eczema.

CONCLUSION

Obviously, A. onychocola is more prevalent than has been assumed up to now. Geophilic dermatophytes detected on atopic dermatitis are not necessarily pathogenetically relevant for eczema-such a colonization needs to be critically interpreted in relation to its clinical context. The determinants that allow geophilic dermatophytes to persist on human skin are still not understood.