What is erythrasma?
Erythrasma is a common skin condition affecting the skin folds such as under the arms, in the groin and between the toes.
Who gets erythrasma?
Erythrasma affects males and females, but it is thought to be more common in the groin of males and between the toes of females.
It is reported to be more prevalent in the following circumstances:
- Warm climate
- Excessive sweating
- Skin of colour
- Poor hygiene
- Advanced age
- Other immunocompromised states
What causes erythrasma?
The bacteria responsible for erythrasma are gram-positive, non-spore-forming, aerobic or facultative bacilli called Corynebacterium minutissimum.
What are the clinical features of erythrasma?
Erythrasma presents as well-defined pink or brown patches with fine scaling and superficial fissures. Mild itching may be present.
Common sites for erythrasma are armpits, groin and between the toes. Intergluteal fold, submammary, and periumbilical skin may also be affected. Widespread infections are associated with diabetes mellitus.
Erythrasma is classified into 3 types according to location.
- Interdigital erythrasma: between 3rd, 4th and 5th toe web spaces
- Intertriginous erythrasma: in armpits, groin, under the breasts and umbilicus
- Generalised/disciform erythrasma: on the trunk
What are the complications of erythrasma?
Serious complications are very rare. Corynebacteria have been reported to causes abscess, cellulitis, cutaneous granuloma, endocarditis, pyelonephritis, endophthalmitis, arteriovenous fistula infection 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.
- Swab or skin scrapings: microscopy may reveal gram-positive filamentous rods. Methylene blue also stains C minutissimum.
What is the treatment for erythrasma?
Photodynamic therapy using red light (broadband, peak at 635 nm) has also been used to treat patients with erythrasma.
Prevention of erythrasma
Recurrence of erythrasma is common. Antibacterial soap can be used to prevent recurrence. Treatment can be repeated if necessary.