This is a form of patchy baldness. Involves well-defined patches of baldness which result in sections of the scalp appearing white and/or smooth
Alopecia areata is a common form of non-scaring type of 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 alopecia areata, there are other different types of white hair phenomena in this context; including permanent white hair regrowth, spearing of white hair in a patchy pattern or spearing in a diffuse form giving the appearance of the so-called “overnight graying phenomena” or Canitis subita