Vitiligo is a primary, limited or generalized skin pigmentation disorder. It is caused by local pigmentation disorders, hypofunction of the tyrosinase system in the black cells of the skin and hair follicles, resulting in a significant lack of melanocytes in the epidermis, resulting in skin pigmentation loss. The term “vitiligo” is found in the Sui Dynasty’s “Treatise on the Origin of Diseases” written by Chao Yuanfang in 610 AD, which describes vitiligo as “the flesh color of the skin of the face and neck body becomes white and different from the flesh color, and it does not hurt, called vitiligo”.
The skin lesions of vitiligo are local pigment loss spots. It is a creamy white, varying in size from 1 to 2cm to dozens of cm. The shape is variable, generally round, oval, but also unshaped, geometrical or reticulated. The number varies and can occur anywhere in the body, with exposed areas such as the face, the back of the hands, areas with more melanin such as the nipples, and areas prone to friction such as the neck and loincloths. The distribution is often symmetrical, but can also be confined to a certain area or occur unilaterally, or can be distributed along the dermatome. The white spots are well-defined and some have increased pigmentation at the edges, while some have islands of normal skin remaining in the white spots. The hair on the white spots may also turn completely white, and the mucous membrane may also be invaded.
At the beginning of the disease, it is mostly one or several patches of hypopigmentation, and the pigmentation is not completely lost, so it can be indistinguishable from normal skin. The lesions gradually develop and expand, with complete loss of pigmentation, which can fuse with each other and gradually become clearly demarcated from the normal skin. The lesions alternate in development and quiescence, and some patients have obvious seasonality.