Alopecia areata (AA) is a common form of nonscarring hair loss. It is believed to be a consequence of an immune-mediated stimulus, probably involving autoreactive T cells against antigens present in the hair follicle. The exact antigen is still unknown; however, some authors have proposed that melanogenesis-associated molecules might trigger autoimmunity. Although transient white hair regrowth is a common and well-known situation in AA, there are other types of white hair phenomena in this context, including permanent white hair regrowth, sparing of white hair in a patchy pattern, or sparing in a diffuse pattern, giving the appearance of the so-called overnight graying phenomena or canitis subita. In this review, we aim to describe the different clinical aspects of white hair in AA, as well as the proposed pathophysiologic mechanisms involved in this phenomena.

斑秃 (AA) 是一种常见的非疤痕性脱发。它被认为是免疫介导刺激的结果，可能涉及针对毛囊中存在的抗原的自身反应性T 细胞。确切的抗原仍然未知；然而，一些作者提出，黑素生成相关分子可能会引发自身免疫。虽然暂时性白发再生是 AA 中常见且众所周知的情况，但在这种情况下还有其他类型的白发现象，包括永久性白发再生、斑状白发保留或弥漫性白发保留，出现所谓的夜间变白现象或canitis subita。在这篇综述中，我们的目的是描述 AA 中白发的不同临床表现，以及该现象所涉及的病理生理机制。