LAUSR

A 9-year-old boy was assessed because of an erythematous plaque next to the left eye, with micropustules and peripheral scaling (Fig. 1). The lesion had been present for 2 months. A sample was taken for direct examination and another sample for fungal culture by scraping the edge of the lesion with a scalpel and wad of sterile cotton wool. In direct microscopic examination of the sample, with potassium hydroxide 20% and dimethyl sulfoxide 40%, mycelia consistent with a dermatophytic fungus were observed. Scales from the lesion were cultured on Sabouraud chloramphenicol actidione agar plates. After 7 days, flat colonies with a starburst-like pattern at the edge had grown, with a bright yellow color on the front and reverse side of the colony (Fig. 2A and B). A powdery white superficial mycelium developed with light radial folds at the center of the colonies (Fig. 2A). The fungus hydrolyzed urea (Christensen and Maslen urea broth) after 7 days and sporulation did not present on the dextrose potato agar plate after 21 days of incubation. With a VITEK MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry [MALDI-TOF MS], BioMérieux), Arthroderma benhamiae (99.9%) was identified after 7 days of incubation on the potato dextrose agar. Molecular identification of the microorganism was performed in the Mycology Unit of the Spanish Microbiology Center in Majadahonda. The lesion was treated for 1 month with terbinafine cream, but follicular involvement still persisted. Finally, the infection resolved with oral terbinafine 125 mg/d for 4 weeks. The microbiology department of our hospital has recorded 15 cases of ringworm caused by A. benhamiae between 2005 and 2017, mainly in children with transmission by guinea pigs; the first case was in 2010 (Table 1). As in cases reported in the literature, all were cases of inflammatory ringworm. Dermatophytic fungi are usually identified using conventional techniques based on macroscopic and microscopic