None.
2.2.1 Erythrasma
Synonyms
Definition
Superficial infection with diphtheroid bacteria mostly affecting intertriginous areas.
Aetiology & Pathogenesis
Most infections are caused by Corynebacterium minutissimum.
Predisposing factors include obesity, diabetes, profuse sweating, occlusive clothing 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.
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.
Course
Chronic or recurs frequently.
Complications
Scratching with secondary infection with other microbes.
Diagnosis
Wood's light: coral red fluorescence (porphyrins from bacterial metabolism), culture (difficult).
Differential diagnosis
Tinea inguinalis and axillaris; contact dermatitis, pityriasis versicolor.
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).
Differential Diagnosis
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