Hello Thanks for query . Multiple bumps on shaft of the penis and scrotum are mostly multiple Sebaceous Cysts . The scrotal and penile skin is rich in sebaceous glands and hence prone to get more sebaceous cyst due to accumulation of sebum beneath the skin. Normally they fade away without treatment however they need to be treated if increase in size or get infected. Maintaining proper personal hygiene by cleaning genital area is very important to avoid getting these cysts . Please consult qualified General Surgeon for clinical evaluation and further treatment. If needed some of them which are bigger may need to get excised in Toto (Completely along with the sac).