called keratin. Blocked sebaceous glands, swollen hair follicles and excessive testosterone production will cause such cysts.
Generally no treatment is required but they become painful then it means they are infected,Then surgical excision by traditional wide excision, minimal excision, and punch biopsy excision may be required.
If the symptoms persist then it will be best to get it evaluated from a dermatologist.
I hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.