A Baker cyst is a swollen, fluid-filled sac at the back of your knee.
Causes of Baker cysts include conditions or occurrences that affect the joints such as arthritis, inflammation from repetitive stress, or a cartilage injury. Baker cysts can cause inflammation and pain and lower range of motion in your knee.
Physical therapy, fluid draining, and medication can all be used to help treat a Baker cyst.
Pilar cyst
A pilar cyst is a noncancerous, skin-colored, round bump that develops under the surface of your skin. They usually affectTrusted Source the skin on the scalp and results from protein buildup in a hair follicle.
They’re not cancerous, but they can grow to a size that can be uncomfortable.
Mucous cyst
A mucous cyst is a fluid-filled lump that forms on your lip or around your mouth when the salivary glands become plugged with mucus. The most common causes of mucous cysts include:
- lip or cheek biting
- lip piercings
- rupture of the salivary gland
- improper dental hygiene
Mucous cysts will often go away on their own. But if you have recurring or frequent mucous cysts, you may need medical treatment.
Branchial cleft cyst
A branchial cleft cyst is a type of developmental irregularity in which a lump develops on one or both sides of your neck or below your collarbone. It occurs during embryonic developmentTrusted Source when tissues in your neck and collarbone, or branchial cleft, develop differently.
In most cases, a branchial cleft cyst isn’t dangerous. But it may cause skin irritation, skin infection, or — in very rare adult cases — cancer.
Perineural (Tarlov) cyst
A perineural cyst is a fluid-filled sac that forms on the spine.
Causes are unknown, but it may resultTrusted Source from back trauma, including falls, injuries, and heavy exertion.
A perineural cyst can cause pain in your lower back, buttocks, or legs, but this is rare. If you do have symptoms, draining the fluid can help to relieve them.
A pseudocyst shares some of the characteristics of a cyst, but the bump doesn’t have its own lining. Here are three types of pseudocysts.
Folliculitis (ingrown hair cyst)
Folliculitis is an infection of hair follicles. It’s often the result of a fungal or bacterial infection and can often resemble acne.
These pseudocysts are often seen in people who use hair removal methods like shaving or waxing. Ingrown hair cysts are an example of folliculitis. While ingrown hair cysts are possible, if you have bumps that appear near ingrown hairs, there’s a good chance that they’re actually razor bumps instead.
Razor bumps are also known as pseudofolliculitis barbae, which is a type of pseudofolliculitis. Unlike folliculitis, pseudofolliculitis isn’t usually infectious.