Red pimples on the chest and back are mostly seen in acne, especially acne vulgaris, because acne vulgaris may be distributed in the chest and back. Because the sebaceous glands and hair follicles in this part are densely distributed, once there is inflammatory infection or local conditional pathogen infection, such as propionibacterium acnes or Staphylococcus albus, there may be inflammatory manifestations, which are commonly seen acne. It may also be a keloid formed after the trauma in this part, which is generally not easy to fade automatically after formation, and some people may gradually increase and even be accompanied by itching symptoms. In addition, it may be malassezia folliculitis caused by malassezia infection in this area. At this time, red pimples may also be accompanied by itching symptoms of different degrees, but they may generally show inflammatory papules with consistent hair follicles.