Videodermoscopy does not enhance diagnosis of scalp contact dermatitis due to topical minoxidil

Background: Videodermoscopy (VD) is a noninvasive diagnostic tool that provides useful information for the differential diagnosis of scalp disorders.

Objectives: The aim of this study was to investigate if dermoscopy may help the clinician in the diagnosis of contact dermatitis of the scalp.

Materials and methods: We analyzed the dermoscopic images taken from 7 patients with contact dermatitis due to topical minoxidil, 6 patients complaining of intense scalp itching during treatment with topical minoxidil but with negative patch tests and 19 controls. The following dermoscopic patterns described for scalp diseases were evaluated: Vascular patterns (simple loops, twisted loops and arborizing lines), follicular/perifollicular patterns (yellow dots, empty ostia, white dots, peripilar signs), white scales, yellow scales, follicular plugging, hair diameter diversity, honeycomb pattern and short regrowing hairs. Findings were graded from 0-4, according to severity in 20-fold magnifications. Statistical analysis included univariate analysis and Chi-square test by SPSS version 12.

Results: There were no statistical differences in the analysis of the vascular patterns and scales between the 3 groups.

Conclusions: We were not able to detect dermoscopic features that can help the clinician in distinguishing scalp contact dermatitis due to topical minoxidil from other conditions that cause severe scalp itching. In particular, minoxidil contact dermatitis does not produce increase or alterations in the morphology of the scalp vessels or significant scalp scaling when evaluated with dermoscopy.