Pityriasis versicolor (pityriasis versicolor) is commonly known as “sweat spot” or tinea versicolor, is a chronic superficial fungal disease caused by Malassezia involving the keratin layer of the skin. 1. Epidemiology: It is more common in tropical and subtropical areas and in hot and humid environments. Males are significantly more common than females, with a high incidence in young adults. There is obvious intra-family aggregation. The onset of the disease depends on the interaction of genetic predisposition and environmental factors. Susceptibility factors include suppressed immune status, glucocorticoid treatment, diabetes, severe burns, malnutrition, excessive sweating, chronic infection, etc. 2, clinical manifestations: the lesions are characterized by round or oval pigmented and/or hypopigmented spots of soybean to nail cap size, raindrop-shaped or fused into patches, covered with light brown thin bran-like scales. The sebaceous and sweat gland secretion areas such as the chest, back, neck, upper arms, abdomen, perineum, scrotum, foreskin and buttocks may also be involved. In tropical areas, the face and scalp can be involved, and infants often have the first occurrence on the forehead and face. 3.Laboratory examination: microscopic examination of scraped lesion scales can reveal mycelium and yeast cells. 4.Differential diagnosis: It is necessary to differentiate from pityriasis simplex, vitiligo, seborrheic dermatitis, pityriasis rosea, non-pigmented nevus, anemic nevus, pigmented hairy epidermal nevus, etc., mainly relying on fungal examination. 5, Treatment (1) Local treatment: Preferred local treatment, various commercially available topical antifungal drug preparations can be applied, 1~2 times a day, the course of treatment 2-4 weeks. Or apply some lotions, such as 2% ketoconazole lotion, selenium disulfide lotion, etc. (2) Systemic treatment: Applicable to those with large and serious lesions. You can choose itraconazole 200~400mg/d for 7~14 days. Itraconazole 200~400mg/d for 7~14 days, or fluconazole 400mg in one dose, should be combined with local treatment drugs. 6, the prognosis (1) the furunculosis and genetic susceptibility and environmental factors, and Malassezia is our human skin resident flora, drug treatment only to the amount of bacteria inhibited to the development of the threshold below, but can not be permanently removed, so the disease is difficult to eradicate. Changing environmental factors such as wearing breathable clothes, drying immediately after sweating, bathing and changing clothes regularly are helpful to reduce recurrence. (2) Even if the bacteria are removed for a short period of time, it is difficult to restore the skin hypopigmentation spots to normal because the melanocytes in the lesions have been damaged. It is suggested to pay attention to the treatment of this disease to prevent the occurrence of hypopigmentation spots. (3) To prevent recurrence, 2% ketoconazole lotion can be used once a week; or itraconazole or fluconazole 400mg can be taken once a month.