Erythrasma is a common, chronic superficial bacterial infection of the skin caused by Corynebacterium minutissimum. It is characterized by distinct, superficial hyperpigmented or erythematous patches localized to intertriginous areas, especially of the axillae, genitocrural crease, and interdigital web space of the toes. Lesions are often asymptomatic, although pruritus may be present, especially when it affects the genitocrural region. A "disciform" variant (large disc-like lesions) usually occurs outside of intertriginous areas and is associated with type 2 diabetes mellitus. Erythrasma may be acute or chronic. It may be asymptomatic or pruritic.
Obesity, diabetes mellitus, immunosuppression, a history of atopy, and hyperhidrosis are risk factors. All age groups may be affected, but incidence increases with age. The highest incidence is seen in regions of high humidity, especially in the tropics.
Erythrasma is a common chronic skin condition affecting the skin folds. The slowly enlarging patches of pink to brown dry skin are caused by an infection by the bacterium Corynebacterium minutissimum.
Who’s At Risk
Erythrasma can affect people of any age or ethnicity, but it is more common among individuals who live in warm, humid climates. It is also more common in dark-skinned people. Although both sexes are equally affected, men tend to have the groin infection more often than women.
The following conditions may predispose people to erythrasma:
Signs & Symptoms
Erythrasma looks like a patch of pink to red, scaly skin. The border of erythrasma is well-defined, meaning there is a sharp border between the affected patch and the surrounding normal skin. Over time, the pink or red color fades to tan or brown.
Erythrasma is typically located in moist body folds such as:
Under the arms (axillae)
In the groin and inner thighs
Between the toes, especially between the 4th and 5th toes
Less commonly, erythrasma can be found in the buttock crevice or in the folds underneath the breasts. In certain individuals, especially in those with diabetes, the infection can become widespread and can involve the trunk, arms, and legs.
Erythrasma usually causes no symptoms, but some people report mild itching or burning, especially in the groin area.
If you suspect that you have erythrasma, try:
Gently scrubbing the involved area with antibacterial soap
Keeping the involved area dry
Applying over-the-counter creams containing tolnaftate or miconazole
When to Seek Medical Care
If the involved skin does not improve with self-care measures, then you should make an appointment to see a health care provider.
Once the diagnosis of erythrasma is established, the doctor may try one of the following treatments:
Topical antibiotic lotions such as erythromycin or clindamycin
Whitfield's ointment (a mixture of benzoic acid and salicylic acid)
Aluminum chloride solution to inhibit sweating and moisture
Oral antibiotics such as erythromycin or clarithromycin
Bolognia, Jean L., ed. Dermatology, pp.1110, 1128. New York: Mosby, 2003.