Background: Topical antifungal treatment is indicated in tinea of glabrous skin, except in cases of extensive, multiple or recurrent lesions, or immunocompromised patients. However, in daily practice there are cases resistant to topical treatment despite these indications. Parasitism of the hair could be the cause behind the majority of isolated lesions of ringworm of hairless skin with a poor outcome with topical antifungal treatment.
Objectives: To present a prospective observational study of 13 cases of tinea of glabrous skin with topical antifungal resistance during the period 2007-2009.
Methods: Cases were analysed from a clinical, mycological and therapeutic standpoint.
Results: The mean age was 7 years. Eight (62%) patients reported prior contact with an animal and 10 (77%) patients had received topical corticosteroids before visiting the dermatologist. Excoriation was observed in eight (62%) patients, and follicular micropustules were seen in 11 (85%). In all patients, some short thin hairs fell easily on to the slide during the skin scraping. In all patients all the few vellus hairs identified in direct examination were affected. All identified species were zoophilic or geophilic. All cases resolved after oral antifungal treatment.
Conclusions: In tinea of glabrous skin with low response to topical antifungal treatment we must rule out tinea of the vellus hair. Infection by nonanthropophilic dermatophytes, previous corticosteroid therapy and excoriation might be predisposing factors. Parasitism of the vellus hair, observed by direct microscopy, should be another criterion for establishing systemic treatment from the onset, as is the case in tinea capitis.
© 2010 The Authors. Journal Compilation © 2010 British Association of Dermatologists.