Supplementary Material for: Trichonodosis: a case report and literature review

Introduction: Hair shaft disorders include congenital or acquired conditions characterized by structural abnormalities of the hair. Trichonodosis, or knotted hair, is a rare disorder characterized by the presence of knots along the hair shaft. It can occur spontaneously or be induced by mechanical forces.

Case Presentation: An 8-year-old girl presented with short, fine, curly hair since birth. Physical examination revealed diffusely curly scalp hair with visible breakage. Trichoscopy and light microscopy showed knotted hair segments, cortical fractures, and variation in hair shaft thickness. A diagnosis of spontaneous trichonodosis was made. Treatment with topical minoxidil and gentle hair care led to improved hair length and strength over 2 years.

Conclusion: We propose that spontaneous trichonodosis with congenital onset and no mechanical triggers suggests a genetic predisposition. Although treatment options are limited, topical minoxidil may provide therapeutic benefit.

概述：毛干疾病（hair shaft disorders）指以毛发结构异常为特征的先天性或获得性病症。结节性毛发病（trichonodosis），又称打结毛发，是一类罕见的毛干疾病，其特征为毛干上出现结节状结构，可自发性发生，亦可由机械外力诱发。

病例报告：一名8岁女童自出生起即表现为短而细软的卷发。体格检查可见其头皮毛发弥漫性卷曲，并可见明显断发。毛发镜（trichoscopy）与光学显微镜检查显示存在结节状毛发节段、毛皮质断裂以及毛干粗细不均。最终确诊为自发性结节性毛发病。经外用米诺地尔（minoxidil）联合温和护发护理后，患者的毛发长度与强度在2年随访期内得到显著改善。

结论：我们提出，先天性起病且无机械诱因的自发性结节性毛发病提示存在遗传易感性。尽管目前可供选择的治疗手段有限，但外用米诺地尔或可带来治疗获益。