Trichoscopy performed with a handheld dermoscope or a videodermoscope became an indispensable tool in differential diagnosis of hair and scalp diseases. Current research is focusing on trichoscopy of: 1) non-cicatricial alopecia, 2) cicatricial alopecia, 3) hair shaft disorders, and 4) inflammatory scalp diseases. This review summarizes current knowledge in these four fields of research. In all non-cicatricial alopecias presence of empty follicular openings is a common trichoscopy finding. In alopecia areata black dots and micro-exclamation mark hairs and tapered hairs correlate with disease activity, whereas yellow dots and vellus hairs correlate with disease severity. In androgenic alopecia trichoscopy shows hair shaft thickness heterogeneity, multiple thin and vellus hairs, yellow dots, perifollicular discoloration, and predominance of follicular units with only one hair. These features predominate in the frontal area. In all forms of cicatricial alopecia, trichoscopy shows milky-red or ivory-white areas lacking follicular openings. In classic lichen planopilaris trichoscopy shows perifollicular inflammation, tubular perifollicular scaling, elongated, concentric blood vessels and "classic white dots", which merge to form white areas. Frontal fibrosing alopecia shows mild perifollicular scaling. Folliculitis decalvans is characterized by tufted hairs, large follicular pustules with emerging hair shafts and perifollicular starburst pattern hyperplasia. In dissecting cellulitis characteristic findings are "3D" yellow dots imposed over dystrophic hairs, large, yellow amorphous areas and pinpoint white dots with a whitish halo. Trichoscopy is particularly useful to diagnose hair shaft abnormalities in trichorrhexis nodosa, trichorrhexis invaginata, monilethrix, pili torti, and pili annulati. The method may be also useful in diagnosing inflammatory scalp diseases. In discoid lupus erythematosus trichoscopy shows large arborizing vessels and large hyperkeratotic folliculilar yellow dots. Trichoscopy of scalp psoriasis shows regularly distributed twisted and lacelike blood vessels, whereas in seborroic dermatitis thin arborizing vessels may be observed. In tinea capitis trichoscopy shows comma, corkscrew and zigzag hairs. Examination tinea capitis may be facilitated by UV-light enhanced trichoscopy (UVET). In conclusion, trichoscopy is a non-invasive method which may be applied in differential diagnosis of most hair and scalp diseases.

Differential diagnosis of trichotillomania is often difficult in clinical practice. Trichoscopy (hair and scalp dermoscopy) effectively supports differential diagnosis of various hair and scalp diseases. The aim of this study was to assess the usefulness of trichoscopy in diagnosing trichotillomania. The study included 370 patients (44 with trichotillomania, 314 with alopecia areata and 12 with tinea capitis). Statistical analysis revealed that the main and most characteristic trichoscopic findings of trichotillomania are: irregularly broken hairs (44/44; 100% of patients), v-sign (24/44; 57%), flame hairs (11/44; 25%), hair powder (7/44; 16%) and coiled hairs (17/44; 39%). Flame hairs, v-sign, tulip hairs, and hair powder were newly identified in this study. In conclusion, we describe here specific trichoscopy features, which may be applied in quick, non-invasive, in-office differential diagnosis of trichotillomania.

Objective:Establishing the trichoscopy criteria of female androgenic alopecia (FAGA).Design:Trichoscopy images were retrospectively evaluated.Setting:Dermatologic hospital-based clinic and private practice offices.Patients and methods:One hundred and thirty-one females (59 with androgenic alopecia, 33 with chronic telogen effluvium (CTE), 39 healthy controls). The diagnosis was based on clinical examination and confirmed by histopatology.Main Outcome Measure:Trichoscopy results obtained in frontal, occipital and both temporal areas of the scalp under a 20-fold and 70-fold magnification, including average hair thickness, number of 'yellow dots' and vellus hairs, number of hairs in one pilosebaceous unit and percentage of follicular ostia with perifollicullar hyperpigmentation.Results:Average hair thickness in frontal area versus occiput was, respectively, 0.061 ± 0.008 mm versus 0.058 ± 0.007 mm in healthy controls, 0.047 ± 0.007 mm versus 0.052 ± 0.008 mm in androgenic alopecia and 0.056 ± 0.007 mm versus 0.053 ± 0.009 mm in CTE. Mean percentage of thin hairs (< 0.03 mm) in androgenic alopecia was 20.9 ± 12% and was significantly higher than in healthy controls (6.15 ± 4.6%, P < 0.001) or in CTE (10.4 ± 3.9%, P < 0.001). The number of yellow dots, pilosebaceous units with only one hair and with perifollicular hyperpigmentation was significantly increased in androgenic alopecia. Classification and Regression Tree Analysis was performed to establish diagnostic criteria for FAGA.Conclusion:FAGA may be differentiated from CTE based on trichoscopy criteria. Major criteria are ratio of (1) more than four yellow dots in four images (70-fold magnification) in the frontal area, (2) lower average hair thickness in the frontal area compared to the occiput and (3) more than 10% of thin hairs (below 0.03 mm) in the frontal area. Minor criteria encompass increased frontal to occipital ratio of (1) single-hair pilosebaceous units, (2) vellus hairs and (3) perifollicular discoloration. Fulfillment of two major criteria or one major and two minor criteria allows to diagnose FAGA based on trichoscopy with a 98% specificity.

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The diagnosis of alopecia areata is usually based on clinical manifestations. However, there are several hair and scalp disorders that share similar clinical features with alopecia areata, such as tinea capitis, trichotillomania or traction alopecia. Trichoscopy as a fast, non-invasive and easy-to-perform technique may help to identify subtle details and establish the correct diagnosis. The aim of this review is to present the spectrum of trichoscopic findings in alopecia areata. A systematic review of the published work was performed by searching the PubMed, Scopus and EBSCO databases, complemented by a thorough hand search of reference lists. Of 427 articles retrieved, 30 studies were eligible for quantitative analysis. The reported features of alopecia areata were: yellow dots (6-100% patients), short vellus hairs (34-100%), black dots (0-84%), broken hairs (0-71%) and exclamation mark hairs (12-71%). Tapered hairs (5-81%) were reported in few studies, but a relatively high frequency of this finding in alopecia areata may indicate their important role in the differential diagnosis of hair loss. Rarely reported features, which include upright regrowing hairs (11-96%), pigtail (circle) hairs (4-61%) and Pohl-Pinkus constrictions (2-10%), may also be helpful in the diagnosis of alopecia areata. There is no pathognomonic trichoscopic marker for alopecia areata and the most common trichoscopic features are not the most specific. Therefore, the diagnosis should be based on the coexistence of several trichoscopic findings, not on the presence of a single feature.

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Background: Trichoscopy is a newly developed method of hair image analysis, based on videodermoscopy of hair and scalp.Objective: The aim of the study was to establish normal values and set the standard for trichoscopy in female population.Patients and methods: A total of 60 healthy females with no symptoms of hair or scalp diseases in anamnesis, upon clinical examination and in classic hair diagnostic techniques were included into the study. Mean age of these females was 36.5 (19-64) years. Trichoscopy was performed with the use of Fotofinder II. In all patients trichoscopy was performed in four locations (frontal area, occipital area, left and right temporal area). Hair and perifollicular area were evaluated. Measurements were performed with the application of the MoleAnalyzer software.Results: Mean hair thickness was 0.061mm±0.008mm in frontal area vs. 0.057mm±0.007mm in occiput (p<0,001) and vs. 0.058mm ±0.008mm in left temporal area and 0.059mm±0.008mm in right temporal area (p>0.005). The percentage of thin hairs (below 0.03mm) was 5%±4.3 in frontal area vs. 5.5%±4.8 in occiput vs. 6.4%±5.7 in right temporal area. The highest proportion of single-hair pilosebaceous units was observed in the temporal areas (29.1±16.2 vs. 23.2±13.5 in frontal and 18.4±12.1 in occipital areas; p<0.005).Based on study results, the norms for parameters measured in trichoscopy were assessed: mean hair thickness bigger than 0,053mm in frontal area and bigger than 0,050mm in others; percentage of thin hairs should be less than 10% in frontal and occipital area and less than 13% in temporal areas.The percentage of pilosebaceous units with single hair should be less than 35% in frontal area, 30% in occiput and 40% in temporal areas.Yellow dots were seen sporadically and they shouldn't be in a higher number than 3 in 4 fields of vision with 70-fold magnification in frontal area and only 1 in others.Perifollicular discoloration should be lower than 25% for frontal area, lower than 15% in occiput and 20% for temporal areas.Conclusion: A standard procedure to perform trichoscopy (hair and scalp videodermoscopy) for diagnostic purposes was developed. Norms of measurable parameters were established for the population of adult white females.

Genetic hair shaft abnormalities may be diagnosed by trichoscopy in a single diagnostic session without the need of plucking or cutting them for diagnostic purposes.