Trichoscopic Features of Syphilitic Alopecia and Alopecia Areata: A Comparative Study

Figures & data

Table 1 Comparison of Baseline Characteristics Between Syphilitic Alopecia and Alopecia Areata

Variables	Syphilitic Alopecia n = 23	Alopecia Areata n = 46	P-value
Age of disease onset, year, mean ± SD	27.6 ± 8.8	30.9 ± 9.1	0.155
Duration of hair loss, month, median (IQR)	1 (1–3)	2 (1–6)	0.42
Gender, n (%)
● Male	20 (86.9)	35 (76.1)	0.29
● Female	3 (13.1)	11 (23.9)
Pattern of alopecia, n (%)
● Reticular pattern	9 (39.1)	18 (39.1)	1.0
● Patch-type pattern	6 (26.1)	12 (26.1)
● Diffuse pattern	4 (17.4)	8 (17.4)
● Mixed pattern	4 (17.4)	8 (17.4)

Abbreviations: IQR, interquartile range; SD, standard deviation.

Table 2 Comparison of Trichoscopic Features Between Syphilitic Alopecia and Alopecia Areata

Trichoscopic Signs	Syphilitic Alopecia, n (%) n = 23	Alopecia Areata, n (%) n = 46	P-value
Upright regrowing hairs	14 (60.9)	30 (65.2)	0.72
Hypopigmented hair shafts	6 (26.1)	8 (17.4)	0.39
Broken hairs	4 (17.4)	28 (60.9)	<0.001*
Pigtail hairs	2 (8.7)	14 (30.4)	0.043*
Exclamation mark hairs	0	31 (67.4)	<0.001*
Tapered hairs	5 (21.7)	28 (60.9)	0.002*
Angulated hairs/Zigzag hairs	1 (4.3)	12 (26.1)	0.029*
Non-pigmented regrowing hairs	0	16 (34.8)	0.004*
Yellow dots	10 (43.5)	21 (45.6)	0.86
Black dots	6 (26.1)	35 (76.1)	<0.001*
Empty follicles	13 (56.5)	24 (52.2)	0.73
Erythematous background	9 (39.1)	3 (6.5)	0.008*
Telangiectasia	1 (4.3)	0	0.60
Perifollicular scales	2 (8.7)	3 (6.5)	0.74
Interfollicular scales	2 (8.7)	5 (10.9)	0.77

Note: *Statistically significant.

Figure 1 Trichoscopic features of syphilitic alopecia (original magnification x20): (A) empty follicles (yellow circles) and erythematous background; (B) hypopigmented hair shafts (blue arrows) and erythematous background; (C) perifollicular scales, interfollicular scales, and erythematous background (green circle); (D) tapered hairs (red arrows), black dots (red star), and yellow dots (red circle).

Figure 2 Trichoscopic features of alopecia areata (original magnification x20): (A) exclamation mark hair (yellow arrow), angulated/zigzag hairs (yellow star), and hypopigmented hair shafts; (B) exclamation mark hair (blue arrow) and telangiectasia (blue circles); (C) angulated/zigzag hairs (green arrow) and black dots (green circles); (D) exclamation mark hairs, tapered hairs (red star), and non-pigmented regrowing hairs (red arrows).

Table 3 Diagnostic Performance of Trichoscopy Toward Syphilitic Alopecia

Trichoscopic Signs	Sensitivity % (95% CI)	Specificity % (95% CI)	PPV % (95% CI)	NPV % (95% CI)	LR+ (95% CI)	LR- (95% CI)	AUC
Upright regrowing hairs	60.87 (38.54–80.29)	34.78 (21.35–50.25)	31.82 (18.61–47.58)	64.0 (42.52–82.03)	0.93 (0.63–1.37)	1.12 (0.59–2.14)	0.478
Hypopigmented hair shafts	26.09 (10.23–48.41)	82.61 (68.58–92.18)	42.86 (17.66–71.14)	69.09 (55.19–80.86)	1.5 (0.59–3.81)	0.89 (0.67–1.17)	0.543
Broken hairs	17.39 (4.95–38.78)	39.13 (25.09–54.63)	12.5 (3.51–28.99)	48.65 (31.92–65.6)	0.28 (0.11–0.71)	2.11 (1.4–3.16)	0.283
Pigtail hairs	8.7 (1.07–28.04)	69.57 (54.25–82.26)	12.5 (1.55–38.35)	60.38 (46.0–73.55)	0.28 (0.07–1.25)	1.31 (1.04–1.65)	0.391
Exclamation mark hairs	4.17 (0.11–21.12)	32.61 (19.53–48.02)	3.13 (0.08–16.22)	39.47 (24.04–56.61)	0.06 (0.01–0.42)	2.93 (1.92–4.48)	0.184
Tapered hairs	21.74 (7.46–43.7)	39.13 (25.09–54.63)	15.15 (5.11–31.9)	50.0 (32.92–67.08)	0.35 (0.15–0.8)	2.0 (1.31–3.04)	0.304
Angulated hairs/Zigzag hairs	4.35 (0.11–21.95)	73.91 (58.87–85.73)	7.69 (0.19–36.03)	60.71 (46.75–73.5)	0.16 (0.02–1.2)	1.29 (1.06–1.56)	0.391
Non-pigmented vellus hairs	4.17 (0.11–21.12)	65.22 (49.75–78.65)	5.88 (0.15–28.69)	56.6 (42.28–70.16)	0.11 (0.01–0.84)	1.46 (1.17–1.84)	0.347
Yellow dots	43.48 (23.19–65.51)	54.35 (39.01–69.1)	32.26 (16.68–51.37)	65.79 (48.65–80.37)	0.95 (0.54–1.67)	1.04 (0.66–1.62)	0.489
Black dots	26.09 (10.23–48.41)	23.91 (12.59–38.77)	14.63 (5.57–29.17)	39.29 (21.5–59.42)	0.34 (0.16–0.69)	3.09 (1.74–5.46)	0.25
Empty follicles	56.52 (34.49–76.81)	47.83 (32.89–63.05)	35.14 (20.21–52.54)	68.75 (49.99–83.88)	1.08 (0.68–1.7)	0.9 (0.52–1.58)	0.522
Erythematous background	39.13 (19.71–61.46)	93.48 (82.1–98.63)	75.0 (42.81–94.51)	75.44 (62.24–85.87)	6.0 (1.79–20.0)	0.65 (0.46–0.91)	0.663
Telangiectasia	4.35 (0.11–21.95)	97.87 (88.71–99.95)	50.0 (1.26–98.74)	67.65 (55.21–78.49)	2.04 (0.13–31.22)	0.97 (0.88–1.07)	0.511
Perifollicular scales	8.7 (1.07–28.04)	93.48 (82.1–98.63)	40.0 (5.27–85.34)	67.19 (54.31–78.41)	1.33 (0.23–7.42)	0.97 (0.84–1.13)	0.511
Interfollicular scales	8.7 (1.07–28.04)	89.13 (76.43–96.38)	28.57 (3.67–70.96)	66.13 (52.99–77.67)	0.8 (0.16–3.81)	1.02 (0.87–1.2)	0.511

Abbreviations: AUC, area under the Receiver Operating Characteristic curve; CI, confidence interval; LR+, positive likelihood ratio; LR-, negative likelihood ratio; NPV, negative predictive value; PPV, positive predictive value.

Table 4 Diagnostic Performance of Trichoscopy Toward Alopecia Areata

Trichoscopic Signs	Sensitivity % (95% CI)	Specificity % (95% CI)	PPV % (95% CI)	NPV % (95% CI)	LR+ (95% CI)	LR- (95% CI)	AUC
Upright regrowing hairs	65.22 (49.75–78.65)	39.13 (19.71–61.46)	68.18 (52.42–81.39)	36.0 (17.97–57.48)	1.07 (0.72–1.58)	0.88 (0.46–1.69)	0.522
Hypopigmented hair shafts	17.39 (7.82–31.42)	73.91 (51.59–89.77)	57.14 (28.86–82.34)	30.91 (19.14–44.81)	0.66 (0.26–1.69)	1.11 (0.84–1.47)	0.457
Broken hairs	60.87 (45.37–74.91)	82.61 (61.22–95.05)	87.5 (71.01–96.49)	51.35 (34.4–68.08)	3.5 (1.39–8.78)	0.47 (0.31–0.71)	0.717
Pigtail hairs	30.43 (17.74–45.75)	91.3 (71.96–98.93)	87.5 (61.65–98.45)	39.62 (26.45–54.0)	3.5 (0.86–14.11)	0.76 (0.6–0.95)	0.609
Exclamation mark hairs	67.39 (51.98–80.47)	95.83 (78.88–99.89)	96.88 (83.78–99.92)	60.53 (43.39–75.96)	16.17 (2.34–111.34)	0.34 (0.22–51.98)	0.816
Tapered hairs	60.87 (45.37–74.91)	78.26 (56.3–92.54)	84.85 (68.1–94.89)	50.0 (32.92–67.08)	2.8 (1.24–6.28)	0.5 (0.32–0.76)	0.696
Angulated hairs/Zigzag hairs	26.09 (14.27–41.13)	95.65 (78.05–99.89)	92.31 (63.97–99.81)	39.29 (26.5–53.25)	6.0 (0.83–43.35)	0.77 (0.63–0.93)	0.609
Non-pigmented vellus hairs	34.78 (21.35–50.25)	95.83 (78.88–99.89)	94.12 (71.31–95.85)	43.4 (29.84–57.72)	8.34 (1.17–59.2)	0.68 (0.54–0.85)	0.653
Yellow dots	45.65 (30.9–60.99)	56.52 (34.49–76.81)	67.74 (48.63–83.32)	34.21 (19.63–51.35)	1.05 (0.59–1.84)	0.96 (0.61–1.5)	0.511
Black dots	76.09 (61.23–87.41)	73.91 (51.59–89.77)	85.37 (70.83–94.43)	60.71 (40.58–78.5)	2.91 (1.43–5.91)	0.32 (0.18–0.57)	0.75
Empty follicles	52.17 (36.95–67.71)	43.48 (23.19–65.51)	64.86 (47.46–79.79)	31.25 (16.12–50.01)	0.92 (0.58–1.45)	1.1 (0.63–1.91)	0.478
Erythematous background	6.52 (1.37–17.9)	60.87 (38.54–80.29)	25.0 (5.49–57.19)	24.56 (14.13–37.76)	0.16 (0.04–0.55)	1.53 (1.09–2.14)	0.337
Telangiectasia	2.13 (0.05–11.29)	95.65 (78.05–99.89)	50.0 (1.26–98.74)	32.35 (21.51–44.79)	0.48 (0.03–7.47)	1.02 (0.92–1.12)	0.489
Perifollicular scales	6.52 (1.37–17.9)	91.3 (71.96–98.93)	60.0 (14.66–94.73)	32.81 (21.59–45.69)	0.75 (0.13–4.17)	1.02 (0.88–1.18)	0.489
Interfollicular scales	10.87 (3.62–23.57)	91.3 (71.96–98.93)	71.43 (29.04–96.33)	33.87 (22.33–47.01)	1.25 (0.26–5.95)	0.97 (0.83–1.14)	0.489

Abbreviations: AUC, area under the Receiver Operating Characteristic curve; CI, confidence interval; LR+, positive likelihood ratio; LR-, negative likelihood ratio; NPV, negative predictive value; PPV, positive predictive value.