Sudden growth of bumps on chest may be caused by folliculitis, acne, keloid and other reasons. 1. Folliculitis: some patients have oily skin, if they sweat in hot weather or after a lot of exercise and are not cleaned in time, the metabolites will accumulate in the hair follicles, which is easy to secondary bacteria and other pathogens infections, resulting in an inflammatory reaction of the hair follicles, which manifests itself as bumps on the chest, accompanied by itching and pain symptoms. 2. Acne: is a chronic inflammatory disease that occurs in the sebaceous glands of the hair follicles, can involve the chest, manifested as erythema, papules, pustules and other lesions, can also cause sudden growth of pimples on the chest. 3. Keloid: when the skin is stimulated by trauma or inflammation, the fibrous tissue of the skin is abnormally proliferated due to pathological scarring. It occurs in the chest, shoulders and back and other locations. It can also cause sudden growth of lumps on the chest. There are many reasons for the sudden growth of lumps on the chest, it is recommended to go to the hospital in time to diagnose the cause, and then take appropriate treatment measures according to the specific causes.