Nail dystrophy - 指甲營養不良https://en.wikipedia.org/wiki/Nail_disease
指甲營養不良 (Nail dystrophy) 是由於未知發炎引起的指甲疾病或畸形。大約一半的疑似指甲真菌病例實際上沒有真菌感染。只有一些指甲營養不良。

指甲營養不良常被誤診為甲真菌病並接受治療。在開始抗真菌治療之前,醫療保健提供者應確認真菌感染。對沒有感染的人進行治療是不必要的醫療保健,並且會導致不必要的副作用。

治療
可以嘗試病灶內注射皮質類固醇來治療指甲營養不良。

治療 - 非處方藥
避免可能傷害腳趾甲的活動,例如踢足球或遠足。抗真菌治療無效,因為甲營養不良不是由真菌感染引起的。

☆ 德國 Stiftung Warentest 2022 年的結果顯示,消費者對 ModelDerm 的滿意度僅略低於付費遠距醫療諮詢。
  • Median nail dystrophy ― 這不是由真菌感染引起的。
  • 指甲營養不良 (Nail dystrophy) 涉及多個手指。
References Trachyonychia and Twenty-Nail Dystrophy: A Comprehensive Review and Discussion of Diagnostic Accuracy 27843915 
NIH
粗甲,或 twenty-nail dystrophy ,是指指甲又薄又脆,有許多縱向的脊。有時, twenty-nail dystrophy 被錯誤地用來描述影響所有二十個指甲的其他情況。
The term trachyonychia, also known as twenty-nail dystrophy, is used to describe thin, brittle nails with excessive longitudinal ridging. The term twenty-nail dystrophy has been incorrectly applied to other conditions that can affect all twenty nails.
 Median nail dystrophy - Case reports 33318093 
NIH
一名 34 歲的男子因兩個拇指指甲上有 20 年無痛腫塊而去看醫生。他不記得自己的指甲受傷或感染。兩隻大拇指的中間,有一條筆直的凹槽,形狀像一棵杉樹,上面有紋路。
A 34-year-old man presented to his primary care physician with a 20-year history of painless bilateral thumbnail lesions. The patient had no history of nail trauma or infection. Both thumbs had a central linear depression in a fir tree pattern, surrounded by parallel transverse ridges.
 Nail cosmetics: What a dermatologist should know! 37317711
雖然大多數美甲化妝品通常是安全的,但它們仍然可能導致過敏反應、刺激、感染和機械問題等問題。值得注意的是,許多指甲美容手術是由可能缺乏指甲解剖學和功能知識的美容師而不是皮膚科醫生進行的。此外,美甲店和美容院的衛生習慣各不相同,這可能會導致甲溝炎和因基質損傷而導致的指甲營養不良等急性問題。
While most nail cosmetics are generally safe, they can still lead to issues such as allergic reactions, irritations, infections, and mechanical problems. It's worth noting that many of nail cosmetic procedures are carried out by beauticians who may lack proper knowledge of nail anatomy and function, rather than dermatologists. Additionally, the hygiene practices in nail salons and beauty parlors vary, which can result in acute problems like paronychia and nail dystrophy due to matrix injury.