There are many blood black bumps on the capillaries of the scrotum, which may be caused by pigmented nevus, warts, localized skin infections, etc., and you should consult a doctor in time to find out the cause of the disease. 1. pigmented nevus: it is a benign neoplasm composed of nevus cells and a common benign tumor of the skin, which can occur in any part of the skin, manifesting itself as a uniform color, clear boundary, yellowish, brown or black spots or papules. 2. Warts: by the human papilloma virus infection of the skin mucosa, and the skin surface caused by benign superfluous organisms, can occur in various parts of the body, may also appear black pimples, clinical common warts, flat warts, plantar warts, warts and other types. 3. Localized skin infections: there are hair follicles on the scrotum, and there may be localized hair follicle infections that can lead to the formation of black bumps, which can be accompanied by localized pain, redness and swelling, and so on. This symptom alone is not enough to diagnose the disease, do not rule out that the symptoms are caused by other factors. It is recommended that the patient go to a regular hospital in time, by the doctor to clarify the cause of the disease, to give targeted treatment.