Author: Reviewed and updated by Dr Amanda Oakley Dermatologist, Hamilton, New Zealand; Vanessa Ngan, Staff Writer, June 2014; Dr Jannet Gomez, Postgraduate Student in Clinical Dermatology, Queen Mary University London, United Kingdom, July 2016.
Erythrasma presents as well-defined pink or brown patches with fine scaling and superficial fissures. Mild itching may be present.
The common sites for erythrasma are armpits, groin and between the toes. The intergluteal fold, submammary, and periumbilical skin may also be affected. Widespreadinfections are most often associated with diabetes mellitus.
Erythrasma is classified into three types according to location.
Interdigital erythrasma: between the 3rd, 4th and 5th toe web spaces
Intertriginous erythrasma: in the armpits, groin, under the breasts and umbilicus
Serious complications are very rare. Corynebacteria have been reported to causes abscess, cellulitis, cutaneousgranuloma, endocarditis, pyelonephritis, endophthalmitis, arteriovenous fistulainfection and meningitis.
How is the diagnosis of erythrasma made?
Erythrasma has a typical clinical appearance. Diagnosis may be supported by the following investigations.
Wood lamp skin examination: long wavelength ultraviolet radiation causes erythrasma to fluoresce a coral-pink colour due to coproporphyrin III released by the bacteria. The fluorescence is not seen if the skin has recently been washed because the responsible porphyrin is water soluble.
Swab or skin scrapings: microscopy with periodic acid–Schiff, methenamine silver, or a Gram stain may reveal gram-positive filamentous rods. Methylene blue also stains C. minutissimum.
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