Supplementary Material for: Beyond the Scalp: Bilateral Hand Trichoteiromania Revealed by Trichoscopy - A Case Report

Introduction:
Trichoteiromania is a friction-induced hair-shaft disorder caused by repetitive rubbing/scratching and is often considered the hair-shaft expression of lichen simplex chronicus ("scratching-pseudoalopecia"). It is classically described on the scalp and presents with lichenified plaques and characteristic trichoscopy such as broom hairs and V-hairs. Pruritus or an urge to rub is common and may help distinguish it from trichotillomania (hair pulling), which is often asymptomatic. To date, the condition has been described almost exclusively as a scalp disorder.
Case Presentation:
We report a 55-year-old man working in finance with a 15-year history of asymptomatic skin changes on the dorsal hands, initially unilateral and later bilateral, who was referred because of concern about malignancy. Examination revealed symmetric lichenified plaques with excoriations, erythema, haemorrhagic crusts, and numerous short broken hairs on the dorsal aspects of the index fingers and thumb, as well as bilateral enlarged lunulae of the thumbnails. Trichoscopy was diagnostic, showing broom hairs, V-shaped hairs, short broken hairs at different lengths, perifollicular and interfollicular scale, and irregular perifollicular brown pigmentation, consistent with trichoteiromania. No biopsy was required. The patient was reassured regarding the benign nature of the condition, started on topical urea and clobetasol, and referred for psychiatric follow-up to address the underlying compulsive rubbing behaviour.
Conclusion:
This case represents, to our knowledge, the first description of trichoteiromania affecting a non-scalp site and demonstrates that its full trichoscopic signature can occur on extracranial hair-bearing skin. This case expands the anatomical spectrum of trichoteiromania beyond the scalp and highlights trichoscopy as a rapid, non-invasive tool to attribute hair-shaft damage to chronic friction.

引言：摩擦诱发性毛干疾病（Trichoteiromania）是一类由反复摩擦或搔抓引发的毛干疾病，常被视为慢性单纯性苔藓（lichen simplex chronicus，又称“搔抓性假性脱发”）的毛干表现形式。该病经典好发于头皮，临床表现为苔藓样变斑块，特征性皮肤镜（trichoscopy）表现包括扫帚状发与V形发。患者常伴瘙痒或搔抓冲动，这一特征可与常无自觉症状的拔毛癖（trichotillomania，即毛发牵拉障碍）相鉴别。截至目前，该病几乎仅被报道为头皮部位的疾病。
病例报告：我们报告1例55岁男性金融从业者，其手背存在15年无症状皮肤改变，初始为单侧分布，后续进展为双侧，患者因担忧罹患恶性肿瘤而就诊。体格检查可见对称分布的苔藓样变斑块，伴抓痕、红斑、出血性痂；食指背侧及拇指背侧可见大量短断发，双侧拇指指甲的甲月牙均增大。皮肤镜检查明确诊断，可见扫帚状发、V形发、长短不一的短断发、毛囊周围及毛囊间鳞屑，以及不规则的毛囊周围褐色色素沉着，符合摩擦诱发性毛干疾病的表现。无需进行组织活检。医师告知患者该病为良性病变，予外用尿素及氯倍他索治疗，并转诊至精神科评估潜在的强迫性摩擦行为。
结论：据我们所知，本例为首例累及头皮以外部位的摩擦诱发性毛干疾病病例，证实其典型皮肤镜特征可出现于颅外多毛皮肤。本病例拓展了摩擦诱发性毛干疾病的发病解剖范围，使其不再局限于头皮，并凸显皮肤镜可作为快速、无创的工具，用于明确毛干损伤由慢性摩擦所致。