2.2.1 Erythrasma

Grading & Level of Importance: A

Review:

2026

W. Burgdorf, Munich; J. McGrath, London
Revised by E. Gaffal, Magdeburg

Overview:

ICD-11
Synonyms
Definition
Epidemiology
Aetiology & Pathogenesis
Signs & Symptoms
Localisation
Classification
Laboratory & other workups
Dermatopathology
Course
Complications
Diagnosis
Differential Diagnosis
Prevention & Therapy
Special

ICD-11

1C44

Synonyms

None.

Definition

Superficial infection with diphtheroid bacteria mostly affecting intertriginous areas.

Epidemiology

Erythrasma mostly occurs in healthy adults, less often in children. Epidemiology is difficult to assess since many patients do not seek treatment or have subclinical infections.

Aetiology & Pathogenesis

Most infections are caused by Corynebacterium minutissimum.

Predisposing factors include obesity, diabetes, profuse sweating, occlusive clothing and a warm humid climate.

Most infections are caused by porphyrin-producing Corynebacterium minutissimum. Predisposing factors are obesity, diabetes, immune suppression (e.g. HIV infection), extensive sweating and a warm humid climate.

Signs & Symptoms

Sharply demarcated, red-brown, scaly patches, occasionally pruritic.

Localisation

Axillary, inguinal, toe clefts. Occasionally sub-mammary areas or extensive.

Axillary, inguinal, toe clefts, genitals, inner aspect of the thigh, submammary areas.

Classification

Interdigital erythrasma, intertriginous erythrasma, generalized/disciform erythrasma.

Laboratory & other workups

None.

Dermatopathology

Orthokeratosis with a minimal perivascular infiltrate in H&E staining. Gram staining shows positive rods and filaments in the stratum corneum.

Mild hyperkeratosis, acanthosis or parakeratosis with a minimal perivascular infiltrate in H&E staining. Gram staining shows positive rods and filaments in the stratum corneum.

Course

Chronic or recurs frequently.

Complications

Scratching with secondary infection with other microbes.

Chronification.

Diagnosis

Wood's light: coral red fluorescence (porphyrins from bacterial metabolism), culture (difficult).

Differential Diagnosis

Tinea inguinalis and axillaris; contact dermatitis, pityriasis versicolor.

Pityriasis versicolor
Tinea inguinalis
Lichen simplex chronicus
Candidosis
Psoriasis vulgaris

Prevention & Therapy

Topical treatment including antiseptics, ciclopirox, or imidazoles (clotrimazole, econazole), sometimes antibiotics (erythromycin). Severe cases can be treated with oral antibiotics (tetracycline, clarithromycin). Disappearance of red fluorescence indicates therapeutic success, hyperpigmentation may persist.

Avoid provoking factors (see above).

Prevention: avoid skin to skin contact in intertriginous areas such as groins, submammary or folds at lower abdomen in obesitas often been occlusive and wet. Obese and diabetics should dry properly and apply adstringens powder.

Treatment: Topical treatment including antiseptics, antimycotic therapy with azoles e.g. clotrimazole or ketoconazole or topical antibiotics e.g. erythromycin or fusidic acid. Severe cases can be treated with oral antibiotics (tetracycline, clarithromycin). Disappearance of red fluorescence indicates therapeutic success; hyperpigmentation may persist.