Using dermoscopy to detect tinea of vellus hair.

DEAR EDITOR, Classically, systemic antifungal treatment is usually mandatory in ringworm affecting cutaneous appendages: the hair or nails. In contrast, in the hairless skin only topical treatment can be used, except in cases of extensive, multiple or recurrent lesions, or in immunocompromised patients. Recently, we described in this journal a new criterion to start systemic antifungal therapy in tinea of vellus hair skin: the observation of parasitized vellus hairs on direct examination. To date, 20 isolated cases of ringworm of the vellus hair have been described, and we reported the largest series of tinea of the vellus hair. We highlighted the potential importance of this finding, which is one cause of resistance to topical treatment in tinea of vellus hair skin. We assessed whether dermoscopy could be useful to identify parasitism of vellus hair, in the same way that it has proven useful in the diagnosis of tinea capitis. We present a prospective observational study of six patients with tinea of vellus hair skin who attended our mycology unit at the Regional University Hospital of Malaga, Spain, during the period 2011–2014. Cases were analysed from a clinical, dermoscopic, mycological and therapeutic standpoint. All patients underwent the following: history taking, clinical examination, digital photography of any lesion using a Canon PowerShot G11 camera (Canon, Lake Success, NY, U.S.A.), microscopic examination of skin scraping, and use of KOH 20%. Fungal culture was performed on Sabouraud dextrose agar with and without actidione, incubated at 27 °C and examined frequently for 3 weeks. Dermoscopic examination (DermLite Pro II HR; 3Gen Inc., San Juan Capistrano, CA, U.S.A.) using a transparent film dressing was performed, after disinfection of the lens with an alcohol swab to avoid transmission of infection. The patients (three male and three female) were aged 4–40 years (mean 20 8). Six patients had single ringworm lesions at the time of diagnosis (Table 1). Most (67%) had received topical antifungal agents before seeing the dermatologist, and two cases (33%) had received topical corticosteroids before. Fifty per cent reported previous contact with a pet. Two patients had lesions located on the arm (Figs 1a, 2a), one on the axillae, one on the chest, one on the leg and one on the cheek (Figs 1a, 2a). Clinically, follicular micropustules were seen in four lesions (67%). Under dermoscopy (Figs 1b, 2b) we observed scaly plaques (100%), translucent hairs (83%), follicular pustules (67%), broken hairs (50%), corkscrew hair (17%), black dots (17%), dystrophic hair (17%) and Morse code hair (17%). Empty follicles were observed in only one lesion. In all cases, during the skin scraping, short thin hairs fell easily onto the slide (Fig. 1c). In all patients all the few vellus hairs identified on direct examination with KOH were affected (Fig. 2c). When antifungal topical cream had been used previously there was no evidence of parasitism of the scales, with the condition of the infected vellus hair being the only finding under direct microscopy; this occurred in five lesions (83%). Geophilic species were identified in one lesion (17%), with the remaining cases all being zoophilic (50%) or anthropophilic species (33%). All cases healed properly after 6 weeks of oral antifungal treatment, with no recurrences. We used griseofulvin when Microsporum canis or Microsporum gypseum were isolated, and terbinafine in the remaining cases.