Pityriasis vulgaris, commonly known as “sweat spot”, is a chronic superficial fungal disease caused by Malassezia involving the stratum corneum of the skin. It was once called lichen planus, because the causative organism is not dermatophytes, so mycologists suggest using the name of the disease. 1. Clinical features: It is more frequent in tropical and subtropical areas and in hot and humid environments. It is significantly more common in males than females and has significant intra-family aggregation. The lesions are round or ovoid hyperpigmented 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. Scraping lesion scales microscopic examination can be seen mycelium and spores. 2, treatment: local treatment is the main, a variety of topical antifungal drugs, such as clotrimazole, miconazole, ketoconazole, econazole, bifenbendazole, sertaconazole, naftifine, terbinafine, boutinafine, amorolfine, ciclopirox, liranafil, etc. can be applied, 1 to 2 times a day, a course of 2 weeks. Those with extensive lesions can be washed externally with some drug shampoos, such as 2% ketoconazole lotion, selenium disulfide lotion, etc. For those with large and severe lesions, oral itraconazole can be used for treatment. But this disease is not easy to cure, easy to recur, can use 2% ketoconazole lotion once a week topically to prevent recurrence. Pityriasis pilaris is easy to cause post-inflammatory hypopigmentation spot (pale white spot), not easy to restore normal, it is recommended that the disease should be treated as soon as possible.