Coral-Red Fluorescence of Erythrasma Plaque

Abstract

A 50-year-old man presented to the Department of Dermatology, University Hospital Complex of Granada, Granada, Spain, in 2015 with a slightly pruritic rash on the left groin, which he had had for two years. He had attended the hospital previously and been diagnosed with eczema and tinea cruris. This had been treated with topical steroids and antifungal drugs (methylprednisolone and sertaconazole) for several months without improvement. A physical examination of the patient showed a diffuse, brownish, well-defined, scaly plaque in the left inguinal region [ Figure 1A]. A potassium hydroxide preparation of tissue scrapings was negative for fungal elements or cultures. The coralred fluorescence of the plaque under a Wood's lamp (WL) examination was characteristic of erythrasma [ Figure 1B]. The patient was treated with 500 mg of oral erythromycin every 12 hours for 14 days, with progressive healing observed over three weeks. CommentErythrasma is a localised and chronic skin infection caused by Corynebacterium minutissimum.

Role of dermatoscopy and the use of ultraviolet-induced fluorescence dermatoscopy in the diagnosis of erythrasma and other skin infections

“…On ultraviolet-induced fluorescence dermatoscopy (UVFD) (365 nm, DermLite-DL5), a small patch of coral-red fluorescence and peri-pilar yellow-green fluorescence was appreciated around a few hair shafts in the right axilla2 3 (figure 2). A 1×3 mm patch of coral-red fluorescence was also appreciated in the left axilla (figure 2), helping confirm the diagnosis of erythrasma and trichomycosis (trichobacteriosis) axillaris 1. The patient was treated with a local application of 2% fusidic acid cream two times per day for 2 weeks and was advised to keep the area clean and dry.…”

“…Microscopic examination of a 20% potassium hydroxide (KOH) mount of the skin scrapings from the groin lesions revealed no fungal hyphae, ruling out dermatophyte infections. However, Wood’s lamp examination of the groin in a dark room showed bright coral-red fluorescence1 (figure 1). Contact dermatoscopy (DermLite DL5) of bilateral axillary areas revealed the prominence of hyperpigmented skin markings, mild scaling and a few hair shafts with yellow, flame-shaped concretions (figure 2).…”

“…(B,C) Wood’s light examination of the groin (365 nm UV light). Characteristic coral-red fluorescence 1…”

Treatment of erythrasma: A double-blinded randomized controlled trial on the clinical application of clotrimazole and sertaconazole

“…26 However, some studies rule this drug out by reporting low or no efficacy on treating erythrasma with sertaconazole. 12,27 This can be due to the late manifestation of drug effects, as a two-month window is usually considered to be necessary for sertaconazole to present the remission. 28 Other drugs are useful at the treatment of erythrasma either, as many studies support the prescription of systemic tablets or local ointments.…”