Girls with chest acne may be related to diseases such as Malassezia folliculitis and acne. 1. Malassezia folliculitis: Malassezia folliculitis is an inflammatory damage of hair follicles caused by Malassezia bacteria. It mostly affects young and middle-aged people, and is more common in males than females. It occurs in the neck, forehead, shoulders and back, and is mostly symmetrical. Typical lesions are inflammatory follicular papules, papules or small pustules, hemispherical, surrounded by a red halo, often tens to hundreds of dense or scattered distribution. 2. Acne: Acne is a chronic inflammatory skin disease of the follicular sebaceous gland units, with lesions occurring on the cheeks and forehead, followed by the chest, back and shoulders, mostly symmetrically distributed, often accompanied by enlarged pores and seborrhea. The various types of lesions include acne at the mouth of the hair follicle, inflammatory papules, pustules, as well as nodules, cysts and scarring. There are more causes of acne on girls’ chests, and it is recommended to go to a regular hospital for examination to clarify the cause.