Hair dye: A trichoscopy pitfall

Hair and scalp disorders account for a large proportion of the presenting complaints to dermatologists. Trichoscopy (dermoscopy of the hair and scalp) serves as a very important diagnostic tool. 1 Miteva M. Tosti A. Hair and scalp dermoscopy. J Am Acad Dermatol. 2012; 67: 1040-1048 Abstract Full Text Full Text PDF PubMed Scopus (215) Google Scholar However, evaluation of the hair and scalp may be additionally challenging if the patient has a history of hair dye use. Permanent and semipermanent hair dyes can mimic distinct pathologies. Permanent hair dye may penetrate hair follicles, giving a “black dot” appearance that is characteristic of active alopecia areata (Fig 1). Semipermanent hair dye can deposit on the scalp and resemble excoriated lesions (Fig 2) or sun damage to the unsuspecting eye. Long-term contact of dyes with the scalp may lead to contact dermatitis, which has been shown to cause telogen effluvium. 2 Tosti A. Piraccini B.M. van Neste D.J. Telogen effluvium after allergic contact dermatitis of the scalp. Arch Dermatol. 2001; 137: 187-190 PubMed Google Scholar Fig 2Patient with semipermanent hair dye appearing as excoriated lesions on the scalp. The surrounding dyed hairs of similar color suggest the correct diagnosis. View Large Image Figure Viewer Download Hi-res image