Dermoscopic Approach to a Small Round to Oval Hairless Patch on the Scalp

BACKGROUND: Various kinds of alopecia can show small round or oval hairless patch. Dermoscopy could be a simple, useful tool for making a correct diagnosis. OBJECTIVE: The aim of this study is to investigate clinical usefulness of dermoscopy for diseases with small round or oval hairless patch on the scalp. METHODS: Dermoscopic examination was performed for 148 patients with small round or oval hairless patch using DermLite® II pro. The type and its patient number of alopecia investigated in the study were as below: alopecia areata (n=81), trichotillomania (n=24), tinea captis (n=13), traction alopecia (n=12), lichen planopilaris (n=8), discoid lupus erythematosus (n=7), congenital triangular alopecia (n=2) and pseudopelade of Brocq (n=1). The significance of dermoscopic findings for each disease were evaluated. RESULTS: Characteristic dermoscopic findings of alopecia areata were tapering hairs and yellow dots. Those of trichotillomania and traction alopecia were broken hairs. Dermoscopic findings of tinea capitis included bent hairs, perifollicular white macules and greasy scales. Discoid lupus erythematosus and lichen planopilaris were characterized by dermoscopic findings of lack of follicular ostia. Furthermore, keratin plugs were frequently seen in discoid lupus erythematosus whereas perifollicular hyperkeratosis and erythema were frequently seen in lichen planopilaris. CONCLUSION: Dermoscopic examination for small round or oval hairless patch showed characteristic findings for each disease. Based on these results, we propose dermoscopic algorithm for small round or oval hairless patch on the scalp.