Back shoulder long pimples do not hurt, a little odor, clinical possible causes are folliculitis, sebaceous cysts, epidermal cysts and so on. 1. Folliculitis: the case refers to an inflammatory skin disease mainly involving hair follicles, and its main clinical manifestations for the hair follicles as the center of the red papules, accompanied by itching, pain, and other symptoms, serious pustules will appear on the affected area, pustules rupture after the pain relieved or even disappeared, and there may be a foul smell. 2. Sebaceous cysts: the situation refers to a sebum gradually silt and form cysts of benign skin lesions, which is usually associated with the follicle sebaceous gland mouth blockage, do not pay attention to personal hygiene and regular cleaning, will cause the above situation, the clinical manifestations of the affected area has a single or multiple small cysts, which will also overflow white content, with a bad smell. 3. Epidermal cysts: due to hereditary or traumatic epidermal ectopic hyperplasia caused by the formation of subcutaneous swelling, the center may have a small hole. It can also lead to a lump on the back of the shoulder without pain, and the effluent has a bad odor. There may be other causes of the above situation, if the situation persists or has a tendency to worsen, it is recommended to go to the hospital dermatology department as soon as possible, to receive standardized treatment.