Dermoscopy of Hair and Scalp Disorders (Trichoscopy) in Skin of Color—A Systematic Review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Abstract

Hair and scalp disorders are of significant interest for physicians dealing with dark phototypes due to their prevalence and potential aesthetic impact resulting from a higher tendency for scarring. In order to facilitate their non-invasive diagnosis, several dermoscopic studies have been published, yet data are sparse and no systematic analysis of the literature has been performed so far. This systematic literature review summarizes published data on trichoscopy of hair and scalp diseases (trichoscopic findings, used setting, pathological correlation, and level of evidence of studies). A total of 60 papers addressing 19 different disorders (eight non-cicatricial alopecias, nine cicatricial alopecias, and two hair shaft disorders) were assessed, for a total of 2636 instances. They included one cross-sectional analysis, 20 case-control studies, 25 case-series, and 14 single case-reports, so the level of evidence was V and IV in 65% and 33% of cases, respectively, with only one study showing a level of evidence of III. Notably, although there is a considerable body of literature on trichoscopy of hair/scalp diseases, our review underlined that potentially significant variables (e.g., disease stage or hair texture) are often not taken into account in published analyses, with possible biases on trichoscopic patterns, especially when it comes to hair shaft changes. Further analyses considering all such issues are therefore needed.

Dermoscopy in Skin of Color: The Journey So Far

“…Interestingly, trichoscopy showed the highest ratio between published studies and number of diseases (60 and 19, respectively) with consequent more data on reproducibility of the findings [8], unlike skin tumors that were investigated by a limited number of studies (20 for a total of 46 neoplasms) possibly due to their lower prevalence in skin of color [9]. Moving to the temporal distribution of published articles (Figure 2), while a more stable publication ratio per year was observed over the time for both hair diseases and tumors, the number of articles on inflammatory and infectious dermatoses showed a remarkable leap over the last few years, with most papers being published during the last six years [6][7][8][9]. Regarding the number of newly described diseases (Figure 3), a significant increase was found in recent times, with peaks in 2017 and 2021 for tumors, in 2019 for infectious dermatoses, and in 2020 for inflammatory disorders [6][7][8][9].…”

“…Inflammatory and infectious dermatoses turned out to have the highest number of published articles (85 and 66, respectively), encompassing a total of 78 and 41 different conditions, likely as the result of the wider number of entities in these fields and their high prevalence in dark-skinned populations [ 6 , 7 ]. Interestingly, trichoscopy showed the highest ratio between published studies and number of diseases (60 and 19, respectively) with consequent more data on reproducibility of the findings [ 8 ], unlike skin tumors that were investigated by a limited number of studies (20 for a total of 46 neoplasms) possibly due to their lower prevalence in skin of color [ 9 ]. Figure 1 depicts clinical subcategories of described dermatoses for each field (inflammatory, infectious, hair and neoplastic disorders), with the following conditions being the most represented ones: (I) papulosquamous and pigmentary dermatoses; (II) parasitoses (including bites and stings), bacterial and fungal diseases; (III) adnexal, keratinocytic and vascular tumors; and (IV) cicatricial and non-cicatricial alopecias [ 6 – 9 ].…”

“…lability of pigment and tendency to follicular or sclerotic reactions) [5]. However, literature evidence on dark phototypes is still limited (<3% of all published papers on dermoscopy) and sparse [6][7][8][9]. This special issue of Dermatology Practical & Conceptual (DPC) provides the readers with an up-to-date literature overview about the use of dermoscopy in dark skin.…”

“…This special issue of Dermatology Practical & Conceptual (DPC) provides the readers with an up-to-date literature overview about the use of dermoscopy in dark skin. Most of included data comes from four systematic reviews (one each for inflammatory, infectious, neoplastic and hair diseases) by the "Imaging in Skin of Color" Task Force of the International Dermoscopy Society (IDS) [6][7][8][9], that has recently been created. Inflammatory and infectious dermatoses turned out to have the highest number of published articles (85 and 66, respectively), encompassing a total of 78 and 41 different conditions, likely as the result of the wider number of entities in these fields and their high prevalence in dark-skinned populations [6,7].…”

“…Inflammatory and infectious dermatoses turned out to have the highest number of published articles (85 and 66, respectively), encompassing a total of 78 and 41 different conditions, likely as the result of the wider number of entities in these fields and their high prevalence in dark-skinned populations [6,7]. Interestingly, trichoscopy showed the highest ratio between published studies and number of diseases (60 and 19, respectively) with consequent more data on reproducibility of the findings [8], unlike skin tumors that were investigated by a limited number of studies (20 for a total of 46 neoplasms) possibly due to their lower prevalence in skin of color [9]. Moving to the temporal distribution of published articles (Figure 2), while a more stable publication ratio per year was observed over the time for both hair diseases and tumors, the number of articles on inflammatory and infectious dermatoses showed a remarkable leap over the last few years, with most papers being published during the last six years [6][7][8][9].…”