Hello Thanks for query. Multiple small lumps on scrotal sac are mostly small sebaceous Cysts . The scrotal 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. 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). Maintaining a proper personal hygiene by cleaning and washing genitals twice daily will help to prevent the recurrence of getting these cysts. Dr.Patil.