Many people use the term “sebaceous cyst” for a small, round lump under the skin, but in many cases the bump is actually an epidermoid or epidermal inclusion cyst. These cysts are usually harmless, grow slowly, and often do not need treatment unless they become painful, inflamed, infected, or bothersome.
What causes a sebaceous cyst?
These cysts can form when surface skin cells move deeper into the skin instead of shedding normally, or when there is irritation, injury, or blockage involving a hair follicle. Cleveland Clinic also notes that epidermal inclusion cysts can form after a blockage at the top of a hair follicle.
