Yellow pimple-like spots on the scrotum are likely to be due to prominent sebaceous glands and this is also known as fordyce spots. They are usually multiple and are not due to STDs or cancer. They are harmless and need no treatment. Epidermal cysts also present as lumps on the scrotum. They are larger than fordyce spots and some can grow pretty big.
Some STDs can present with bumps on the scrotum too. Molluscum contagiosum can appear as small whitish or red bumps on the scrotum too but they often also affect areas beyond the scrotum.
If you have any doubts, you should see your doctor/dermatolgist for further examination to confirm the diagnosis.
Hope this helps!
