This disease occurs in young and middle-aged women, mostly in late spring and early summer, and naturally recovers in autumn and winter. Skin lesions often occur in parts exposed to the sun, especially on the face and neck. The rash is polymorphic and the course of disease is about 3 ~ 5 months. According to the shape of the rash, it can be divided into four types.
1. macula is a red or dark red infiltrating plaque, which is mostly located in the sun. If it is serious and lasts for a long time, peripheral telangiectasia and abnormal skin color may occur. After the rash subsides, there is pigmentation and itching. .
2. Erythema multiforme rash is a red or dark red edematous papule with different sizes, clear boundaries and slightly raised edges.
3. Eczema-type skin is flushed and swollen, with pimples, blisters, erosion, scabbing and desquamation on the surface, which look like eczema, sometimes lichen-like, and consciously itch.
4. Itching rash is erythema, papules and nodules the size of rice grains to mung beans. The course of the disease may be lichenoid. After regression, there is pigmentation and spontaneous itching.