Introduction

Tinea capitis (TC) is the most common dermatophytosis in children [1, 2]. In some situations, the appearance and clinical context are not obvious requiring mycological confirmation. However, the culture results can take 4 weeks to be available, which may hinder the management of these patients and increase the risk of contamination [3]. In these cases, trichoscopy can guide the diagnosis. Therefore, dermoscopic signs specific to TC must be well established.

Materials and method

We carried out a 6-month prospective descriptive analytical study between January and June 2017, gathering the various dermoscopic signs found in children with alopecic plaques suspected of TC. We classified them according to the clinical patterns of microsporic TC, trichophytic TC, or inflammatory TC, in order to find a correlation between the dermoscopic signs and the clinical subtype. The data were saved on Excel and analyzed on the SPSS Statistics version 20 software.

Results

We collected data from a total of 34 children with alopecic plaques highly suggestive of the diagnosis of TC. The average age of our patients was 8.42 years (3–14 years). Out of the 34 children, 67.6% were boys and 32.4% girls, with a sex ratio of 2.09. Out of the 34 children, 47.51% had microsporic TC, 29.4% trichophytic TC, and 23.5% inflammatory TC (Table 1). Only six patients were able to have a mycological culture to confirm the diagnosis of TC as well as the clinical subtype; all the children received probabilistic treatment with good evolution. The other 28 patients did not have a mycological culture because of a lack of financial means. Under the dermoscope, the signs found were: broken hair (91.2%), follicular keratosis (82.4%), scales (85.3%), black dots (73.5%), bent hair (70.6%), erythema (64.7%), comma hairs (55.9%), crusts (50%), corkscrew hairs (35.3%), forked hairs (32.4%), bar code-like hair (26.5%), follicular pustules (23.5%), zigzag hair (17.6%), translucent hair (11.8%), and V-shaped hair (11.8%; Fig. 1). We did not observe a classic dermoscopic sign of alopecia areata.

Table 1 Patient characteristics
Full size table
Fig. 1
figure 1

Dermoscopic signs

Full size image

Univariate analysis showed that: the sign of corkscrew hair was significantly present in female children (p < 0.05, r = 0.016), comma hair and corkscrew hair were found in microsporic TC (p < 0.001, r = 0.685 and p < 0.05, r = 0.536, respectively; Figs. 2 and 3), V-shaped hair was mainly seen in inflammatory TC (p < 0.05, r = 0.017; Figs. 4 and 5), crusts and follicular pustules in inflammatory TC (p < 0.05, r = 0.061 and p < 0.001, r = 0.000, respectively; Fig. 6), scales and follicular keratosis in non-inflammatory TC (p < 0.001, r = 0.000 and p < 0.05, r = 0.038, respectively; Figs. 7 and 8), and, finally, erythema was seen in trichophytic and inflammatory TC (p < 0.001, r = 0.889; Table 2).

Fig. 2
figure 2

Microsporic tinea due to Microsporum canis with single squamous plaque of alopecia in parietal region

Full size image
Fig. 3
figure 3

Dermoscopic image corresponding to the inset square of Fig. 2

Full size image
Fig. 4
figure 4

Inflammatory tinea

Full size image
Fig. 5
figure 5

Dermoscopic image corresponding to the inset rectangle of Fig. 4

Full size image
Fig. 6
figure 6

Dermoscopic image corresponding to the inset rectangle of Fig. 4

Full size image
Fig. 7
figure 7

Tinea due to Trichophyton violaceum with diffuse small plaques of alopecia

Full size image
Fig. 8
figure 8

Dermoscopic image corresponding to the inset rectangle of Fig. 7. The orange arrowheads are pointing for scales and follicular keratosis, the yellow ones for broken hairs, the blue ones for bent hairs

Full size image
Table 2 Univariate analysis
Full size table

Discussion

In 2008, Slowinska et al. described for the first time the sign of comma hair in two children with TC [4]. In 2011, Hughes et al. reported the sign of corkscrew hair in six black children, especially in cases of Trichophyton soudanense infection [5]. The authors suggested that corkscrew hair could be a variant of comma hair in black patients, or a specificity of TC due to Trichophyton soudanense [5]. Our study confirms the specificity of these two signs in TC since they disappeared during probabilistic treatment (Figs. 9 and 10). These two signs are often found simultaneously, with the same patient, which could be explained by the fact that our population is of an intermediate skin phototype (Fig. 11).

Fig. 9
figure 9

Pre-therapeutic dermoscopy showing specific signs of tinea capitis. The white arrowheads are pointing for follicular keratosis, the red ones for question mark hair

Full size image
Fig. 10
figure 10

Dermoscopy 6 weeks after probabilistic treatment of the plaque shown in Fig. 11

Full size image
Fig. 11
figure 11

Dermoscopy showing an association of corkscrew hair (black circle) and comma hair (white circle) in the same patient due to tinea capitis

Full size image

A study carried out in 2015 on four patients with microsporic tinea and two with trichophytic tinea showed that comma hair was specific to trichophytic tinea caused by Trichophyton tonsurans, while the bent hair of microsporic tinea was caused by Microsporum canis [6]. The Bourezane and Bourezane study of 24 patients with TC showed that infection caused by endothrix agents was responsible for abnormalities in hair shape, infection caused by ectothrix agents was responsible for abnormalities in hair color, and finally infection caused by both ectothrix and endothrix agents presented as a mixed dermoscopic pattern [7]. This is in contrast to the results of our study, where comma hairs and corkscrew hairs were significantly present in microsporic tinea (Figs. 3 and 12).

Fig. 12
figure 12

Dermoscopy showing an association of comma hair (white circle) and corkscrew hair (black circle) in a patient with tinea due to Microsporum canis

Full size image

These results seem interesting when considering the choice of probabilistic treatment, especially with the emergence of species more sensitive to terbinafine than to griseofulvin. As reported in the guidelines of management of TC in England, the first-line treatment is terbinafine for trichophytic tinea, which is an allylamine that acts on the cell membrane and is fungicidal, and griseofulvin for microsporic tinea, which is a fungistatic drug that inhibits nucleic acid synthesis, arrests cell division at metaphase, and impairs synthesis of the cell wall [8, 9]. However, these studies require a broader validation; in particular, some studies have not confirmed the correlations between dermoscopic signs and the type of pathogen [10,11,12].

Other studies have highlighted the importance of trichoscopy in monitoring patients with TC [13, 14].

Limitations of the study

Mycological confirmation (direct examination and culture) was not available for all patients. The authors classified patients according to the clinical pattern, in microscopic TC, trichophytic TC, or inflammatory TC, in order to make a correlation between the dermoscopic signs and the clinical subtype.

Conclusion

In conclusion, trichoscopy is a simple, fast, and inexpensive method for diagnosing and monitoring TC in children. However, mycology remains the gold standard for diagnostic confirmation, which is also inexpensive but can take a long time. Confirmation of our results by dermoscopy/mycology correlation in large studies will allow us to treat patients only on the basis of the dermoscopic signs.