Abstract
Reproduced with permission from DermNet New Zealand.
Case study
A 42-year-old male presents with a 3-month history of a slightly itchy brown rash in his axillae. The rash is slowly spreading. He has a history of diabetes.
This is erythrasma
The rash is usually caused by bacteria called Corynebacterium minutissimum. It is more common in warm climates and in patients with diabetes. Erythrasma may be confused or co-exist with other causes of intertrigo, for example tinea or candida.
The rash is usually asymptomatic, but can be itchy. Any age group can be affected, but it is more common in adults. The rash is mainly located in the toe clefts and flexural areas, for example groins, axillae and sub-mammary areas. Infection gives rise to slowly enlarging, irregular, well-demarcated brown or pink patches.
Diagnosis is usually clinical, but exposure to Wood’s light
Treatment includes topical anti-bacterials, for example fusidic acid, clindamycin solution and Whitfield’s ointment. For cases not responding to this, good results have been reported with a single dose of clarithromycin 1 g, or a short course of erythromycin or tetracycline. Phototherapy has also been used.
Recurrences may be reduced by advising weight loss, keeping skin dry and using anti-septic washes. Complications are rare, but include contact dermatitis, lichenification, pigmentation and co-infection.