There are a lot of pimples on the upper side of the back firstly consider whether it is acne, and secondly consider the possibility of Malassezia folliculitis, which needs to be analyzed specifically. 1. Acne: Acne is a chronic inflammatory skin disease of the sebaceous gland units of the hair follicles, lesions occurring on the cheeks, forehead, followed by the chest, back and shoulders, mostly symmetrical distribution, often accompanied by enlarged pores and seborrhea. The lesions include acne, inflammatory papules, pustules, nodules, cysts and scarring at the mouth of the follicle. 2. Malassezia folliculitis: is caused by Malassezia follicular inflammatory damage. It occurs in the neck, chest, shoulders and back, and is mostly symmetrical. Typical lesions are inflammatory follicular papules, papules or small pustules, hemispherical, surrounded by a red halo, which can be squeezed out of the powdery substance, often dozens to hundreds of dense or scattered distribution. The back of the upper side of a lot of pimples may also have other reasons, it is recommended to go to the hospital in a timely manner, standardized treatment.