Sciatica long a soft bag in the middle of a small black spot, may be localized folliculitis, sebaceous cysts and other causes. Localized folliculitis is a kind of acute bacterial infectious disease, mainly because of, staphylococcus aureus infection caused by the early stage, often lead to local redness, swelling and hot pain, with the progress of the disease, may lead to the formation of abscess, manifested as a soft bag, when pressed, the pain will be more obvious. In addition, there may also be sebaceous cysts, mainly due to excessive sebum secretion, stagnation of the formation of a kind of skin changes, there may be bacterial infections, resulting in localized significant swelling, feel the soft bag. Sciatica at a soft bag in the middle of a black spot, if accompanied by pain symptoms, should be timely consultation to identify the cause, in order to carry out targeted treatment.