Evelyn:
They are a kind of cyst, which many
womenWomen's way (and men) have around their nipples. The "white
substanceDrug abuse" is
regularRegular insulin cust contents -- dead skin cells, etc. -- rather than pus. There's no need to do anything about these cysts, though light electrocautery can minimize them if they embarrass you. The're not related to keratosis pilaris, which consists of bumps of keratin protein on the outer arms.
Best. Dr. R
Show 'em to your doc next visit, just to be sure.
Dr. R