If scalp cysts become infected, the doctor prescribes an antibiotic, and if the patient chooses, the doctor removes the cyst, according to WebMD. The procedure leaves a scar, and cysts have the ability to grow back on the scalp. The most common type of scalp cyst is a pilar cyst.
Pilar cysts are composed of keratin, which makes up the top skin layer and hairs. In appearance, it looks like runny toothpaste or cottage cheese. On the inside, the pilar cyst has a lining of cells that are similar to the ones at the bottom of the hair follicle. When cells that typically stay near the skin's surface move down into deeper parts, they keep multiplying and create a sac while secreting keratin. This is what they would also do if they were still on the top layer, but their relocation causes this process to form a cyst, as stated by WebMD.
Pilar cysts grow slowly and look like domed, circular bumps beneath the skin. They range from pea-sized to several centimeters across. Because they do not usually cause any medical problems, treatment for pilar cysts is often unnecessary until they cause issues. They do not develop into cancer, they don't spread, and they aren't contagious, as stated by WebMD.