A Single Typical Trichoscopic Feature Is Predictive of Tinea Capitis
A Single Typical Trichoscopic Feature Is Predictive of Tinea Capitis
TAKE-HOME MESSAGE
- Trichoscopic findings from 100 patients with presumed tinea capitis were compared with those obtained from a mycological culture, which is considered the gold standard for diagnosis. Results showed that the culture was positive in 53 patients, whereas the sensitivity and specificity of trichoscopy was 94% and 83%, respectively. Although different features—such as comma hairs, corkscrew hairs, zigzag hairs, Morse code–like hairs, and whitish sheath—were significantly more frequent in the positive culture group, the presence of a single feature in trichoscopy was predictive of tinea capitis.
- These findings suggest that trichoscopy can be a useful, rapid, and highly sensitive tool for the diagnosis of tinea capitis, and it can help the physician with diagnosis and treatment of the type of dermatophyte involved.
– Caroline K. Crabtree, MD
- Written by
This prospective study performed in four French university-based dermatology departments investigated the diagnostic accuracy of trichoscopy to establish the diagnosis of tinea capitis (TC). The patient population was predominantly children <13 years of age, with a median age of 6.24 years.
The study involved 100 patients coming to the ambulatory clinics for suspected TC. The trichoscopy procedures were performed by dermatology residents with no previous training in trichoscopy except that they had been shown pictures or drawings of comma hairs, corkscrew hairs, zigzag hairs, Morse-code hairs, and whitish sheath. During the study, each clinical trichoscopic image obtained by the resident was reviewed by an expert. The trichoscopy was considered positive if at least one specific TC sign was noted on at least two hairs. Samples for mycologic culture were also obtained.
The authors found that the presence of just a single feature (including comma hairs, corkscrew hairs, zigzag hairs, Morse-code hairs, or whitish sheath) resulted in a sensitivity for the diagnosis of TC of 94%, a specificity of 83%, a positive predictive value of 92%, and a negative predictive value of 86%. Not only did trichoscopy help establish the diagnosis, but also it was helpful in identifying the underlying likely organism. Morse-code like and/or zigzag hairs indicated Microsporum TC but comma hairs suggested Trichophyton TC. Additionally, ethnic differences were appreciated. African-type infected TC hairs more commonly demonstrated comma hairs than Caucasian-type hairs, whereas Caucasian TC-infected hair usually displayed Morse code–like hairs and/or zigzag hairs. Finally, the study revealed a difference between ectothrix and endothrix infections. Ectothrix infections mostly demonstrated Morse code–like hairs and/or zigzag hairs, while endothrix more commonly demonstrated comma and/or corkscrew hairs.
This study demonstrates additional reasons that a dermatologist should always have a dermatoscope in his or her pocket. It helps reduce the number of unnecessary biopsies by distinguishing between benign and potentially malignant lesions, and is also useful for many inflammatory dermatoses and infections.
BACKGROUND
Specific trichoscopic signs of tinea capitis (TC) were first described in 2008. The accuracy of this diagnostic tool has not been evaluated.
OBJECTIVES
To assess the diagnostic accuracy of trichoscopy.
METHODS
A prospective, multicentre study was done between March 2015 and March 2017 at the dermatology departments of four French university medical centres. Patients with a presumed diagnosis of TC were included. Trichoscopy was considered to be positive if at least one specific trichoscopic sign was observed. Trichoscopy results were compared with the gold standard for diagnosis of TC (mycological culture).
RESULTS
One hundred patients were included. Culture was positive for 53 patients and negative for 47. The sensitivity of trichoscopy was 94% [95% confidence interval (CI) 88-100], specificity was 83% (95% CI 72-94), positive predictive value was 92% and negative predictive value was 86%. Comma hairs, corkscrew hairs, zigzag hairs, Morse-code-like hairs and whitish sheath were significantly more frequent in patients with a positive mycological culture (P < 0·001). Comma hairs were more frequent in patients with Trichophyton TC (P = 0·026), and zigzag hairs were more frequent in patients with Microsporum TC (P < 0·001). Morse-code-like hair was not observed in any patients with Trichophyton TC and therefore appears to be highly specific for Microsporum TC.
CONCLUSIONS
The presence of a single trichoscopic finding is predictive of TC. Trichoscopy is a useful, rapid, painless, highly sensitive tool for the diagnosis of TC - even for dermoscopists with little experience of trichoscopy. It enhances physicians' ability to make treatment decisions.
A Single Typical Trichoscopic Feature Is Predictive of Tinea Capitis: A Prospective Multicentre Study
Br J Dermatol 2019 Mar 07;[EPub Ahead of Print], F Dhaille, AS Dillies, F Dessirier, P Reygagne, M Diouf, T Baltazard, F Lombart, V Hébert, M Chopinaud, L Verneuil, C Becquart, E Delaporte, C Lok, G ChabySkin Care Physicians of Costa Rica
Clinica Victoria en San Pedro: 4000-1054
Momentum Escazu: 2101-9574
Please excuse the shortness of this message, as it has been sent from
a mobile device.
posted by dermatica at
May 17, 2019
0 Comments:
Post a Comment
Subscribe to Post Comments [Atom]
<< Home