Nail dystrophy - 指甲营养不良https://en.wikipedia.org/wiki/Nail_disease
指甲营养不良 (Nail dystrophy) 是一种由未知炎症导致的指甲疾病或畸形。约有一半的疑似甲真菌病病例实际上并无真菌感染,只有少数是真正的指甲营养不良。

指甲营养不良常被误诊为甲真菌病并接受治疗。开始抗真菌治疗前,医疗提供者应先确认是否存在真菌感染。对未感染者进行治疗既是无效的医疗干预,也会带来不必要的副作用。

治疗
可尝试在病灶内注射皮质类固醇以改善指甲营养不良。

治疗 - 非处方药
避免可能损伤脚趾甲的活动,如踢足球或徒步旅行。抗真菌治疗无效,因为指甲营养不良并非由真菌感染引起。

☆ 德国 Stiftung Warentest 2022 年的结果显示,消费者对 ModelDerm 的满意度仅略低于付费远程医疗咨询。
  • Median nail dystrophy ― 这不是由真菌感染引起的。
  • 指甲营养不良 (Nail dystrophy) 涉及多个手指。
References Trachyonychia and Twenty-Nail Dystrophy: A Comprehensive Review and Discussion of Diagnostic Accuracy 27843915 
NIH
twenty-nail dystrophy(粗甲),是指指甲变薄、易碎,并出现许多纵向的脊。有时,twenty-nail dystrophy(粗甲)被错误地用于描述影响全部二十个指甲的其他情况。
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岁的男性因两只拇指指甲上出现已持续20年的无痛肿块前来就诊。他不记得指甲曾受过外伤或感染。两只拇指的指甲中部呈现一条笔直的凹槽,形似杉树,表面有纹理。
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
虽然大多数美甲化妆品通常是安全的,但它们仍可能引起过敏反应、刺激、感染以及机械性问题。值得注意的是,许多指甲美容操作是由可能缺乏指甲解剖学和功能知识的美容师而非皮肤科医生完成的。此外,美甲店和美容院的卫生习惯参差不齐,这可能导致甲沟炎以及因基质受损而引起的指甲营养不良等急性问题。
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.