Dermoscopic Features of Pili Annulati: Features of PA

Dear Editor,

Collect several cases of children with abnormal hair color as a feature. The children's hair began to appear a pale yellow color at birth, and the family denied any history of hair dyeing or contact with anything unusual, but their immediate family members have a relevant medical history. Dermatological examination: normal hair alternating with white hair, overall hair color is pale yellow. Dermoscopy: black and white striped texture, resembling a “zebra stripe” pattern (Figure 1a,b). Diagnosis: pili annulati. No treatment was given and close follow‐up was conducted.

FIGURE 1.

(a) Clinical picture. (b) Dermoscopy: normal black hair (green arrow); white stripes (red arrow); “zebra stripe.”

Pili annulati is a relatively rare disease with genetic predisposition, currently believed to be autosomal dominant inheritance, characterized by alternating black and white hair resembling the appearance of “zebra stripes” [1]. Under the skin microscope, alternating white bands of light yellow hair can be seen, which will help distinguish pili annulati. This color change is believed to be caused by the accumulation of bubbles in the hair cortex and medulla, leading to medullary rupture and enhanced light reflection, resulting in a special appearance. At present, there are not many reports of pili annulati, and the patients and their family members in this article have the same medical history, which can prove that the disease has a genetic predisposition. The tensile strength of the patient's hair is normal, so pili annulati is generally not prone to hair loss, but few people may experience hair loss easily. There is currently no effective treatment for pili annulati that does not affect the quality of life. Some scholars have suggested using minoxidil for treatment, but most children with hair color abnormalities feel that it is attractive and refuse medical treatment [2].

Based on the characteristics of the case in this article and combined with previous literature [3], we believe that pili annulati has the following characteristics: ① It begins in childhood; ② It is an autosomal dominant inheritance; ③ It has a characteristic alternation of normal hair and white hair that is not easily lost; ④ Dermoscopy: black and white striped texture, resembling a “zebra stripe” pattern. Additionally, some scholars have suggested that pili annulati may be combined with alopecia areata, immune thyroid disease, and primary immunoglobulin A deficiency. None of the children in this study had any of the above conditions and this viewpoint has not been widely confirmed, so we have not listed this view as a feature of pili annulati.

We have summarized many characteristics of this disease, which will assist us in the clinical diagnosis of patients suspected of having pili annulati. Especially, dermatoscopy is a non‐invasive tool, which can improve the accuracy of pili annulati diagnosis for pediatric patients. Due to the small sample size, further large‐scale research is needed to improve the skin imaging of pili annulati.

Ethics Statement

The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Tianjin Children′s Hospital.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.