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Erythrasma and similar non-infectious dermatoses
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Mohammad Ghahri   |
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Abstract: (7 Views) |
Pitted keratolysis, trichobacteriosis of the hair shafts of the axilla and pubic skin folds, and erythrasma are three well-known dermatoses caused by species of the genus Corynebacterium. Erythrasma presents clinically as asymptomatic, pruritic lesions, often in skin folds and moist areas. These lesions usually appear as red or brown hyperpigmented patches of skin with central scaling and hypopigmentation, and may be slightly raised. The most common diagnostic test for erythrasma is the Wood's lamp examination. The Wood's lamp is a black light source with a wavelength of 320 to 400 nm, with the most suitable wavelength being 365 nm. The diagnosis of erythrasma can be confirmed by observing coral-red or coral-pink fluorescence on the affected skin during Wood's lamp examination. Porphyrins, mainly coproporphyrin III, produced by corynebacteria are the source of this distinctive fluorescence. Uroporphyrin I has also been associated with the fluorescence of corynebacteria under the Wood's lamp. It is important to note that if the lesion has been recently cleaned and washed with water, the Wood's lamp examination or test will be falsely negative. Differential diagnoses of erythrasma, especially in the groin area, include Candida albicans infection, dermatophyte infection, Malassezia furfur infection (pityriasis versicolor or tinea versicolor), pityriasis rotunda, and terra firma-forme dermatosis. These conditions can present as well-defined, hyperpigmented plaques. However, Wood's lamp examination, potassium hydroxide slide findings, and treatment with 70% isopropyl alcohol can help differentiate these lesions. Pityriasis rotunda is a papulosquamous disease and a keratinization disorder of the skin that appears as perfectly circular, scaly patches on the trunk and proximal extremities (legs and arms). It may be associated with diseases such as hepatocellular carcinoma in susceptible ethnic groups. Terra firma-forme dermatosis is characterized by dirty grayish-brown patches and plaques that can be easily removed by swabbing with alcohol pads. Its pathogenesis has been attributed to abnormal and delayed keratinization. Although affected patients present with typical lesions, the disorder is not recognized by dermatologists. |
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| Keywords: Erythrasma, Corynebacterium, Wood’s Lamp, Dermatose |
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Full-Text [PDF 3627 kb]
(4 Downloads)
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Type of Study: Review |
Subject:
قارچ شناسی
Received: 2026/06/28 | Accepted: 2026/06/28 | Published: 2026/06/28
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