Pictorial Case Study: Erythrasma

The case
This middle-aged man with diabetes had been aware of a rash in his axillae for over a year. Initially he ignored it, but after a time it started to itch and more recently it had become 'rubbed and sore'. At first he assumed that it was a reaction to his deodorant but discontinuation made no difference. A topical hydrocortisone cream from the chemist also failed to help. When he finally consulted the well defined, pinkish/brown, wrinkled, scaly rash was noted in both axillae. What is the diagnosis, management and differential diagnosis?

Diagnosis and management
The diagnosis of erythrasma was confirmed by viewing the affected area under a Wood's lamp in a darkened room: the lesion flouresced a coral red. Also, skin scrapings from the area confirmed the presence of Corynebacterium minutissimum, the cause of erythrasma. As the condition was localised to the axillae the patient was prescribed topical fucidin to be applied three to four times a day and told if the response was incomplete, he could return for a course of erythromycin or tetracycline to clear it. Antibacterial soap was advised to prevent recurrence.

Possible different diagnoses

  • Intertrigo and/or candida.
  • Allergic or irritant contact dermatitis.
  • Plaque psoriasis or seborrhoeic dermatitis.
  • Tinea.

Differential diagnosis
Flexural seborrhoeic dermatitis

  • Occurs after puberty - usually in obese middle-aged patients.
  • Inflammatory reaction to proliferation of a yeast that normally lives on the skin.
  • Secondary bacterial or candida infection is common.
  • Symmetrical, flat, pink or red, raw and sore patches with a fine scale and dryness of the skin.

 

Contributed by Dr Jean Watkins, a GP in Ringwood, Hampshire.

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