Trichoscopic Findings in Normal Hair and Scalp in Children Under 17 Years.

OBJECTIVE: The aim of the study is to establish normal values of measurable parameters, set the standard, and provide a framework for future reference.
MATERIALS AND METHODS: A total of 750 children of Malayalam speaking ethnicity with no hair or scalp diseases in anamnesis and clinical examination were included in the study. Children were divided into six age groups (neonates, infants, 1-5, 6-10, 11-14, and 15-17 years), and trichoscopy was performed in frontal, left and right temporal, vertex, crown, and occiput using Wi-Fi cordless digital dermoscope. Hair shaft, follicular opening, and perifollicular and interfollicular area were evaluated and analyzed with SPSS software.
RESULTS: Among the parameters analyzed, we observed that with 0.95 probability (95%), the terminal: vellus ratios are (26,29), (22,25), (22,26), (29,33), (25,29), and (19,24) in neonates; (11,14), (7,11), (9,13), (13,17), (12,16), and (7,12) in infants; (16,17), (10,11), (10,11), (16,18), (15,16), and (14,15) in 1-5 years; (17,18), (11), (11), (19,21), (23), and (16,17) in 6-10 years; (17,18), (9,10), (10), (19,20), (18,19), and (16,17) in 11-14 years; and (14,15), (8-9), (8,9), (15,16), (14, 16), and (13,14) in 15-17 years. Likewise, we have documented the various trichoscopic findings of different age groups.
CONCLUSION: We propose the summary of trichoscopic patterns of different age groups with normal hair and scalp to accurately identify the abnormal. Copyright:

INTRODUCTION

The total (histologic) follicle density on the scalp is 1135/cm2; however, as the head enlarges progressively up to puberty, the density falls to 795/cm2 at the age of 3–12 months, and 615/cm2 by the third decade.[1] The density of emergent hair shafts is lower than the histologic density of follicles, which is about 500–700 hair cm−1 at birth.[2]

At birth, the shaft is round, and during the first 2 years of life, it assumes an oval cross-section that is maintained throughout life. The cross-sectional area rapidly rises to 0.25 mm2 at the age of 3 years, but thereafter increases more gradually to 0.40 mm2 at the age of 17 years.[3]

The proportion of medullated scalp hairs rises steeply from 0% to 60% from the 3rd to 7th month, falls to 23% at 2 years, and then gradually rises in proportion to cross-sectional area. The medullated, thin hair at 6–18 months is an intermediate form that suddenly replaces vellus and is separate from the succeeding terminal hair.[4]

Brownish perifollicular discoloration, also known as the peripilar sign, may be present in some healthy individuals. Some trichoscopic features such as empty follicular openings, yellow dots, black dots, broken hair, or comma hair occasionally may be seen in healthy individuals; however, studies to support the significance of these findings in children are lacking.[56]

PubMed and Google Scholar databases were searched for eligible articles on the subject of trichoscopy of normal hair and scalp in children. Literature lacks comprehensive assessments on the features of normal hair and scalp characteristics in children under 17 years. To mitigate the problem, in this study, an attempt is made to establish normal values for measurable parameters in children of different age groups, which allows better understanding in clinical practice of what is abnormal in hair and scalp dermoscopy. The aim of the study was to establish the trichoscopic patterns of hair and scalp in healthy children.

MATERIALS AND METHODS

A total of 750 healthy children of Malayalam speaking ethnicity from Thrissur, Kerala, with no symptoms of hair or scalp diseases in anamnesis, on clinical examination, and in classic hair, diagnostic techniques attending the Pediatric and Dermatology Department of Amala Institute of Medical Sciences, Neonatology Unit of Jubilee Mission Hospital, and IES public school between August 2015 and August 2016 were recruited in the study. The study was approved by the local ethics committee.

We considered the definition for a neonate to be “the period of life beginning at birth and lasting through the 28th day of life“[7] and infant as “young children between the ages of 1 month and 12 months.”[8]

Children were divided into six age groups, i.e., neonates (70/750), infants (40/750), 1–5 years (150/750), 6–10 years (160/750), 11–14 years (160/750), and 15–17 years (170/750). Trichoscopy was performed using a handheld nonpolarized contact dermoscope (Wi-Fi cordless digital dermoscope [Derma India]) in six regions, i.e., frontal, left and right temporal, vertex, crown, and occiput.

Settings were manually adjusted to achieve the best picture quality for each specimen. The usual working magnifications are 70-fold which magnifies an area of 8 mm2. A photograph of each area was taken for each child. A photograph of each area was taken for each child. The parameters analyzed were terminal : vellus hair ratio [Figures 1 and 2], number of hair per follicular unit, intermediate hair [Figure 3], new hair, dark lines [Figure 4], comma hair [Figure 5] broken hair, block/I hair [Figure 6], coiled hair [Figure 7], interfollicular area, perifollicular scale [Figure 8], black dots [Figure 9], hemorrhagic dots [Figure 10], dirty dots [Figure 11], and density covering an area of 8 mm2. Terminal: vellus ratio, intermediate hair, new hair, and density were expressed in terms of confidence interval. Analysis was performed with the use of IBM SPSS Statistics for windows, version 20.0 (Armonk, NY:IBM Corp.).

Figure 1

Vellus hair (4-year-old male, frontal area)

Figure 2

Terminal hair (16-year-old male, frontal area)

Figure 3

Intermediate hair (17-year-old female, left temporal area)

Figure 4

Dark line (5-year-old female, left temporal area)

Figure 5

Comma hair (15-year-old female, frontal area)

Figure 6

Block hair (45-day-old male, occipital area)

Figure 7

Coiled hair (5-year-old female, frontal area)

Figure 8

Perifollicular scale (5-year-old female, frontal area)

Figure 9

Black dot (15-year-old female, left temporal area)

Figure 10

Hemorrhagic dot and pediculi (Pediculosis) (5-year-old female, frontal area)

Figure 11

Dirty dot (2-year-old female, vertex area)

RESULTS

Data obtained from trichoscopic analyses of 750 children are summarized in [Chart 1], Table 1 and 2. Parameters such as terminal: vellus ratio, intermediate hair, new hair, and density are expressed in terms of 95% confidence interval. Parameters such as number of hair per follicular unit, zigzag hair [Figure 12], pigtail hair [Figure 13], widespread thin hair (WTH) [Figure 14], comma hair, block/i hair, coiled hair, dark line, perifollicular halo, perifollicular scale, casts [Figure 15], black dots, dirty dots, and hemorrhagic dots are expressed in terms of percentage [Tables 2 and 3]. All participants had skin types III, IV, or V. 64.66% were boys and 35.34% were girls.

Chart 1

Trichoscopic findings (Expressed in terms of percentage) (n = 750). (a and e) Casts and perifollicular scale are absent in neonates and infants. (b and d) Coiled hair and perifollicular halo are absent in infants and 15-17 years. (c) Comma hairs are absent in infants, 6-10 years, and 11-14 years. (f) Zigzag hairs are absent in neonates, infants, and 15-17 years

Table 1

Trichoscopic findings (expressed in terms of confidence interval) (n=750)

Parameter	Age group	Frontal	Right temporal	Left temporal	Vertex	Crown	Occiput
Terminal: vellus ratio [Figures 1 and 2]	Neonate	26,29	22,25	22,26	29,33	25,29	19,24
	Infant	11,14	7,11	9,13	13,17	12,16	7,12
	1-5	16,17	10,11	10,11	16,18	15,16	14,15
	6-10	17,18	11,11	11,11	19,21	23	16,17
	11-14	17,18	9,10	10,10	19,20	18,19	16,17
	15-17	14,15	8,9	8,9	15,16	14,16	13,14
Intermediate hair [Figure 3]	Neonate	1,2	1,2	1,2	1,2	1,1	1,2
	Infant	1,2	1,2	1,2	0,1	0,2	0,1
	1-5	0,0	0,0	0,0	0,0	0,0	0,0
	6-10	1,1	0,0	0,0	0,1	0,1	0,1
	11-14	1,1	0,1	0,1	0,0	0,1	0,1
	15-17	0,0	0,0	0,0	0,0	0,0	0,0
New hair [Figure 16]	Neonate	1,2	0,1	0,1	1,1	0,1	0,1
	Infant	0,1	0,1	0,1	0,1	0,2	0,1
	1-5	1,1	0,0	0,1	0,1	0,0	0,1
	6-10	1,1	0,0	0,0	0,0	0,0	0,1
	11-14	0,1	0,0	0,0	0,0	0,0	0,0
	15-17	1,1	0,0	0,0	0,0	0,0	0,1
Density	Neonate	28,32	25,28	24,28	32,36	27,31	22,27
	Infant	15,20	12,17	13,17	16,20	17,24	14,20
	1-5	18,19	10,11	11,12	17,19	16,17	15,17
	6-10	20,21	11,12	11,12	20,22	19,20	18,19
	11-14	19,21	10,11	11,12	19,20	18,20	17,19
	15-17	16,17	9,10	9,10	16,17	15,16	14,15

Table 2

Trichoscopic findings (expressed in terms of percentage) (n=750)

Parameter	Age group	Frontal, n (%)	Right temporal, n (%)	Left temporal, n (%)	Vertex, n (%)	Crown, n (%)	Occiput, n (%)
Hemorrhagic dot	Neonate	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)
	Infant	1 (1.3)2 (0.7)	1 (1.3)2 (0.7)3 (0.7)	1 (0.7)2 (1.3)3 (1.3)5 (4)	2 (2)	1 (2)	0 (100)
	1-5	1 (1.3)2 (0.7)	1 (1.3)2 (0.7)3 (0.7)	1 (0.7)2 (1.3)3 (1.3)5 (4.0)	2 (2.0)	1 (0.7)	0 (100)
	6-10	1 (2.5)2 (0.6)	2 (0.6)	2 (0.6)	1 (1.3)3 (0.6)5 (1.3)	3 (0.6)	0 (100)
	11-14	2 (1.3)	1 (0.6)2 (0.6)	1 (0.6)	0 (100)	1 (1.3)5 (0.6)	0 (100)
	15-17	1 (1.2)	1 (0.6)	1 (1.8)	1 (0.6)	1 (0.6)	1 (0.6)
Black dot	Neonate	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)	0 (100)
	Infant	0 (100)	0 (100)	0 (100)	1 (2.5)	0 (100)	0 (100)
	1-5	1 (4)2 (3.3)4 (0.7)	1 (2)2 (2.7)3 (0.7)	1 (6)2 (1.3)	1 (1.3)2 (0.7)3 (0.7)4 (0.7)5 (0.7)	1 (2.7)2 (1.3)3 (0.7)4 (0.7)	1 (2.7)2 (2.7)3 (0.7)
	6-10	1 (0.6)	0 (100)	0 (100)	2 (0.6)	1 (0.6)3 (0.6)	0 (100)
	11-14	1 (0.6)	1 (0.6)	0 (100)	1 (1.3)	1 (1.9)2 (0.6)	0 (100)
	15-17	1 (1.2)	0 (100)	1 (0.6)	2 (0.6)	2 (0.6)	0 (100)
Dirty dot*	Neonate	0 (100)	Few (1.4)	1 (1.4)2 (1.4)4 (2.9)Few (1.4)	1 (1.4)2 (1.4)	0 (100)	2 (1.4)
	Infant	3 (2.5)9 (5)Few (2.5)	Few (2.5)	4 (2.5)9 (2.5)	1 (2.5)9 (2.5)	1 (2.5)Few (7.5)	1 (2.5)4 (2.5)
	1-5	1 (3.3)	1 (3.3)2 (3.3)3 (1.3)6 (0.7)Few (4.7)	1 (0.7)2 (1.3)3 (2.7)5 (0.7)Few (6)	1 (2)2 (3.3)3 (1.3)5 (0.7)Few (10)	1 (1.3)2 (3.3)4 (1.3)5 (0.7)Few (6.7)	1 (0.7)2 (5.3)3 (1.3)Few (5.3)
		2 (3.3)3 (2.7)4 (0.7)5 (0.7)Few (9.3)
	6-10	1 (1.3)2 (5)3 (1.3)4 (5)6 (0.6)11 (0.6)Few (6.9)	1 (2.5)2 (8.1)3 (3.1)4 (1.9)5 (0.6)7 (0.6)Few (8.1)	1 (3.1)2 (6.9)3 (3.1)4 (2.5)8 (0.6)Few (7.5)	1 (6.3)2 (4.4)3 (1.9)4 (0.6)5 (0.6)6 (0.6)7 (0.6)Few (5.6)	1 (5)2 (3.1)3 (1.9)6 (0.6)7 (0.6)Few (11.3)	1 (5.6)2 (3.1)3 (2.5)10 (0.6)12 (3.8)
	11-14	1 (5.6)2 (6.3)3 (1.9)4 (0.6)Few (3.1)	1 (3.1)2 (5)3 (1.3)4 (1.9)Few (1.9)	1 (6.3)2 (3.1)5 (0.6)6 (0.6)Few (1.9)	1 (5)2 (7.5)3 (1.3)Few (6.3)	1 (5)2 (5.6)3 (1.9)5 (1.3)Few (1.3)	1 (2.5)2 (3.1)Few (0.6)
	15-17	1 (0.6)2 (2.4)Few (2.9)	1 (1.8)2 (3.5)Few (0.6)	1 (1.2)4 (0.6)Few (0.6)	1 (0.6)2 (1.2)Few (3.5)	1 (1.8)Few (1.2)	1 (1.8)2 (1.8)4 (0.6)10 (0.6)
Number of hair per follicular unit	Neonate	1 (57.1)1,2 (42.9)	1 (20.0)2 (11.4)1,2 (62.9)2,3 (2.9)1,2,3 (2.9)	1 (21.4)2 (8.6)1,2 (65.7)2,3 (2.9)1,2,3 (1.4)	1 (22.9)2 (18.6)1,2 (52.9)2,3 (4.3)1,2,3 (1.4)	1 (18.6)2 (14.3)1,2 (57.1)2,3 (5.7)1,2,3 (4.3)	1 (21.4)2 (18.6)1,2(55.7)2,3 (1.4)1,2,3 (2.9)
	Infant	1 (60)1,2 (40)	1 (52.5)2 (22.5)1,2 (22.5)1,2,3 (2.5)	1 (60.0)2 (12.5)1,2 (25.0)2,3 (2.5)	1 (50.0)2 (10.0)1,2 (32.5)2,3 (5.0)1,2,3 (2.5)	1 (37.5)2 (22.5)1,2 (32.5)2,3 (7.5)	1 (50.0)2 (25.0)1,2 (22.5)2,3 (2.5)
	1-5	1 (5.3)2 (23.3)3 (0.7)1,2 (48.0)2,3 (19.3)1,3 (2.0)	1 (2.0)2 (32.7)1,2 (32.0)2,3 (29.3)1,2,3 (4.0)	1 (2.0)2 (32.0)3 (1.3)1,2 (30.7)2,3 (30.0)1,3 (0.7)1,2,3 (3.3)	1 (1.3)2 (26.7)3 (1.3)1,2 (20.0)2,3 (46.0)1,2,3 (4.0)	1 (0.7)2 (32.7)3 (1.3)1,2 (19.3)2,3 (40.0)3,4 (1.3)	1 (0.7)2 (42.0)1,2 (18.0)2,3 (38.0)1,2,3 (1.3)
		1,2,3 (1.3)			2,4 (0.7)	2,4(1.3)1,2,3(3.3)
	6-10	1 (25.0)2 (8.1)1,2 (51.3)2,3 (10.0)1,2,3 (5.6)	1 (0.6)2 (24.4)1,2 (44.4)2,3 (23.8)1,2,3 (6.9)	1 (4.4)2 (25.6)1,2 (49.4)2,3 (8.1)1,2,3 (12.5)	1 (1.3)2 (19.4)3 (0.6)1,2 (33.8)2,3 (35.0)1,2,3 (8.8)2,3,4 (1.3)	1 (0.6)2 (28.8)3 (1.3)1,2 (33.1)2,3 (30.6)1,2,3 (5.6)	1 (1.3)2 (43.1)3 (2.5)1,2 (21.3)2,3 (24.4)1,3 (0.6)1,2,3 (6.3)2,3,4 (0.6)
	11-14	1 (21.9)2 (8.1)1,2 (56.3)2,3 (4.4)1,2,3 (9.4)	1 (1.9)2 (30.6)3 (0.6)1,2 (39.4)2,3 (21.3)1,3 (1.3)1,2,3 (5.0)	1 (5.0)2 (30.0)1,2 (36.3)2,3 (21.9)1,2,3 (6.9)	1 (0.6)2 (16.9)3 (0.6)1,2 (37.5)2,3 (27.5)1,3 (1.3)1,2,3 (13.1)2,4 (0.6)2,3,4 (1.9)	2 (23.1)3 (3.8)1,2 (24.4)2,3 (32.5)1,3 (1.3)1,2,3 (13.1)2,4 (0.6)2,3,4 (1.3)	2 (28.1)3 (2.5)1,2 (20.6)2,3 (40.6)1,3 (0.6)1,2,3 (5.0)2,3,4 (1.9)1,2,4 (0.6)
	15-17	1 (20.6)2 (18.8)3 (0.6)1,2 (44.1)2,3 (14.7)1,2,3 (1.2)	1 (5.9)2 (32.4)3 (0.6)1,2 (37.6)2,3 (20.0)1,2,3 (3.5)	1 (6.5)2 (34.7)3 (1.2)1,2 (40.0)2,3 (15.3)1,3 (0.6)1,2,3 (1.8)	1 (1.8)2 (25.3)3 (2.9)1,2 (27.1)2,3 (37.6)1,2,3 (2.4)3,4 (0.6)2,4 (1.2)2,3,4 (0.6)1,2,4 (0.6)	1 (0.6)2 (22.9)3 (4.1)1,2 (18.8)2,3 (48.2)1,2,3 (3.5)2,4 (1.2)2,3,4 (0.6)	1 (1.8)2 (34.1)3 (2.9)1,2 (10.0)2,3 (47.6)1,2,3 (1.8)3,4 (0.6)2,4 (1.2)
Block hair	Neonate	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)
	Infant	1 (2.5)2 (5.0)4 (5.0)6 (2.5)7 (5.0)8 (5.0)14 (2.5)18 (2.5)26 (2.5)	1 (5.0)3 (2.5)4 (5.0)5 (5.0)6 (2.5)8 (5.0)10 (2.5)14 (2.5)21 (5.0)22 (2.5)	1 (2.5)2 (7.5)6 (5.0)7 (7.5)8 (2.5)9 (2.5)12 (2.5)	1 (5.0)2 (15.0)7 (5.0)8 (5.0)9 (2.5)11 (2.5)12 (2.5)	1 (2.5)2 (2.5)3 (7.5)5 (2.5)6 (2.5)8 (2.5)10 (2.5)12 (5.0)32 (2.5)35 (2.5)39 (2.5)	3 (2.5)4 (7.5)5 (2.5)8 (5.0)9 (2.5)13 (2.5)18 (2.5)21 (2.5)22 (2.5)27 (2.5)30 (2.5)
							33 (2.5)38 (2.5)
	1-5	3 (0.7)	0(100.0)	3 (0.7)	1 (0.7)	1 (0.7)	1 (0.7)3 (0.7)4 (0.7)
	6-10	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)	1 (0.6)	0 (100.0)
	11-14	2 (0.6)	1 (0.6)	0 (100.0)	0 (100.0)	2 (0.6)	1 (0.6)
	15-17	0 (100.0)	1 (0.6)	0 (100.0)	1 (0.6)	0 (100.0)	0 (100.0)
Dark line	Neonate	1 (5.7)2 (1.4)3 (1.4)	1 (2.9)2 (1.4)	1 (5.7)2 (1.4)	1 (7.1)2 (2.9)	1 (4.3)	1 (2.9)
	Infant	1 (5.0)	1 (2.5)2 (2.5)	1 (2.5)	1 (2.5)	0 (100.0)	0 (100.0)
	1-5	1 (0.7)	1 (0.7)	0 (100.0)	3 (0.7)	0 (100.0)	1 (2.0)
	6-10	1 (8.1)2 (2.5)4 (0.6)	1 (5.6)2 (0.6)5 (0.6)	1 (3.8)2 (0.6)	1 (5.0)2 (1.9)3 (0.6)	1 (6.3)2 (2.5)	1 (8.1)2 (3.1)3 (1.3)4 (1.3)
	11-14	1 (8.8)2 (4.4)4 (0.6)6 (0.6)8 (0.6)	1 (3.8)2 (1.3)4 (1.3)	1 (5.0)2 (1.3)3 (0.6)	1 (4.4)	1 (1.3)2 (0.6)3 (0.6)	1 (3.8)2 (2.5)
	15-17	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)	0 (100.0)

*Few dirty dots: >11 dirty dots

Figure 12

Zigzag hair (8-year-old female, frontal area)

Figure 13

Pigtail hair (4-day-old male, occipital area)

Figure 14

Widespread thin hair (1-day-old female, occipital area)

Figure 15

Cast (5-year-old female, vertex area)

New hair (16-year-old female, vertex area)

DISCUSSION AND CONCLUSION

This is the first study evaluating different parameters of hair and scalp through dermoscopic examination in a series of 750 healthy children under 17 years. With this study, we propose the norms of measurable parameters, summary and documentation of various trichoscopic patterns in children of different age groups with normal hair and scalp which will, in turn, allow us to accurately identify and treat what is abnormal.

Postnatal hair may be divided at the extreme into two kinds: terminal hairs are long, coarse, often medullated and pigmented, and vellus hairs are soft, unmedullated, occasionally pigmented, and seldom ≥2 cm long.[8] However, Rakowska defines terminal hair as ≥55 μm wide and uniform in thickness and color, and vellus hair as hypopigmented, nonmedullated, <30 μm thick, and <2–3 mm long.[59] In a study by Barth et al., video dermoscopy showed the presence of WTH in 20% of the newborns. These hairs measured 0.04 mm in diameter and 2 cm in length, which is not consistent with either vellus hair (diameter <0.03 mm and length <2 mm) or with terminal hair (diameter >0.06 mm and length >2 mm), but falls within the range of intermediate hair (diameter between 0.03 and 0.06 mm and length >2 mm).[10] In our study, measurement and documentation of hair shaft diameter were beyond the scope of the instrument. Henceforth, in our study, medullated hair, uniform in thickness, and colour have been attributed as terminal hair; fragmented or nonmedullated, sparsely pigmented hair with length ≥ 2 mm have been designated as intermediate hair; and nonmedullated, hypopigmented hair with length <2 mm considered as vellus hair. In our opinion, an accurate description and the essential criteria to designate a particular hair as vellus, intermediate, terminal, and WTH is essential for a better understanding of both normal and abnormal hair in the absence of sophisticated dermoscope.

Surprisingly, in our study, we observed the negligible presence of vellus hair, and instead, the occasional presence of intermediate hair in neonates and infants.

At birth, there are two consecutive waves of hair from the forehead to nape of the neck with the newer wave consisting only of anagen roots, and the previous wave converting to telogen prior to being shed. There is, therefore, a gradual overlap of predominantly second growth over first growth hairs (due to delay in shedding after conversion to telogen). This progression to the second pelage is delayed in infants with a dark complexion who therefore have abundant growth at birth. There is an area over occiput, in which primary hair do not enter telogen until after birth, remain on the scalp for 8–12 weeks and then fall. In the subsequent hair cycle, intermediate hair forms the first scalp hair and asynchronous cycle is established. Subsequently, hair growth is much stronger and consistent in density. On the scalp, fully developed terminal hair follicle is detectable around 12–16 months of age.[11] These facts support our finding, wherein the terminal: vellus ratio and hair density are greater in neonates, falls steeply in infants, gradually increases till 10 years, and decreases slightly thereafter.

Block hair, which are short hair shafts with a horizontal distal end[12] were seen noticeably and hence in infants and children in the age group of 1–5 years due to tonsuring of hair performed during this period.

Zigzag hair/Z hair usually observed in tinea capitis, alopecia areata, and trichorrhexis nodosa, and other diseases that cause focal weakening of hair shaft[13] were occasionally seen in children.

New, upright regrowing hair seen occasionally is a sign of hair regrowth in healthy individuals.[12]

We document, in children, the occasional presence of trichoscopic features such as black dot, comma hair, coiled hair, and broken hair. These findings are similar to that previously described in adults.[56]

The most interesting fact emerging from our study is the presence of dark lines which appear as regrowing hairs that are short, thin, pigmented, darker than the natural color of hair, in which differentiation between proximal and distal ends often is impossible,[14] and which has been described in literature as a trichoscopic finding only in alopecia areata incognito.

Hair cast was infrequently seen in school going healthy children. They may be idiopathic or a sign of traction.[15]

One to four hair per follicular unit emerges from one follicular opening, a finding similar to that seen in adults.[16]

We describe and document the presence of a novel and unique trichoscopic finding of normal scalp examination in children. Hemorrhagic dots, which present on the scalp as red dots corresponding to follicular ostia swollen with blood, were found in school-going children and not at all in neonates or infants. However, the proportion of hemorrhagic dots decreases in older children (1 hemorrhagic dot in 0.5%–1.5% in those aged 15–17 years). This finding suggests improved self-care, hygiene, and grooming practices with an increasing age.

Dirty dots present on the scalp as clumped and haphazardly arranged particulate debris and loose fibers of various colors. Dirty dots represent nonmicrobial environmental particles due to the inability of the scalp to repel particulate debris due to a relative decrease in sebaceous gland activity. According to Fu et al., dirty dots were not found in children younger than 9 months and older than 10 years. In contrast, in our study, we observed its presence in children of all age groups.[17] However, the dots are less numerous in newborn and children older than 15 years.

The normal pattern of sebaceous gland activity in humans is cyclic.[18] There is a strong stimulation of sebum secretion before birth under the influence of dehydroepiandrosterone which probably stops at or soon after birth resulting in very high sebum levels in the 1st week of life of the same magnitude as in adults followed by a fall. The secretion begins to increase in mid to late childhood due to increase in endogenous production of androgens.[19] However, the exact relationship between dirty dots and sebaceous gland activity needs to be elucidated.

However, these are, so far, the most relevant preliminary data emerging from our observation. We hope that a further exhaustive evaluation using advanced digital dermoscope will lead to other important discoveries, and aimed at enriching the present poor knowledge of this fascinating and unprecedented topic.

Limitations of the study

The study is limited by the inability to measure and document hair shaft diameter and variability owing to lack of sophisticated dermoscope like FotoFinder.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.