Hi   Seems like you have developed Acne Corporis lesions. Sometimes acne lesions can occur only over the body.  It is a common skin disease, characterized by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules, nodules (large papules) and possibly scarring. Acne affects mostly skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back.  In your case, you seem to develop acne lesions only over chest and upper arms. This is a common condition especially in adults. Some general advise :  Avoid using any kind of moisturising creams/ lotions or oil over the affected area.  Wear cotton clothes as much as possible  Do not use any liquids like dettol or savlon over the affected area  You can use antibacterial soaps during bathing. You might need to apply some antiacne medications like clindamycin gel over the affected area. But if inspite of the above measures, you continue to develop the lesions, then you might need a course of oral antibiotics,. So I would recommend that you visit a dermatologist in that case for proper examination and treatment . Dr Geetika Paul