You find a bump on the back of your neck and wonder: Is it a cyst? Or an abscess? But wait — is an abscess the same as a cyst?
Confusing the two is easy because they share some similarities. Here’s a look at how cysts and abscesses differ and what to do if you have one or the other.
Is a Cyst the Same as an Abscess?
Cysts and abscesses are both lumps that can appear on the skin or inside the body. But they’re not the same thing.
A cyst is a closed, usually round sac. It may contain debris, air, or fluid. Cysts are usually harmless and not contagious.
An abscess is a pocket of pus typically caused by a bacterial infection. On the skin, it can appear pink or red and feel swollen and painful. The pus from an abscess is extremely contagious.
What Is a Cyst?
A cyst is a round, hard lump just underneath the skin, usually filled with fluid or a material called sebum, an oily substance that protects your skin. It sometimes has a dark spot in the middle. Cysts often occur on the face, head, neck, or back, but you can get them inside your body, too.
Cysts tend to grow slowly. The size of a cyst can vary from pea-sized or smaller to an inch or more across. Most cysts aren’t cancerous — unlike tumors, they have an enclosed sac of skin around them.
The location of a cyst and the membrane covering it tells your doctor what kind of cyst it is.
Three Types of Skin Cysts
Three common types of cysts grow on the skin.
Epidermal (sebaceous) cyst
This type of cyst is very common. Its wall consists of the epidermis, or the outermost layer of skin. Epidermal cysts often appear on the face, ears, back, neck, and scalp.
An epidermal cyst may contain a cheese-like substance called sebum. It can develop a foul smell. The cyst often forms when a hair follicle gets clogged, either from acne or an injury.
Milia
Milia are small, firm, white cysts that usually grow on the face, especially around the eyes. They occur when dead skin cells get trapped under the skin’s surface. Although milia aren’t harmful, many adults opt to have them removed for a better appearance.
You can often see milia on the skin of newborn babies. They typically disappear in infants without treatment.
Pilar (trichilemmal) cyst
A pilar cyst is like an epidermal cyst, except it tends to occur in multiples instead of a single cyst. They often grow on the scalp. Pilar cyst walls are usually thicker than epidermal cyst walls, making it easier to remove them in one piece.
Cysts Inside the Body
Cysts can occur anywhere inside the body. Some of the most common ones are:
- Baker’s cysts — Appear as a swelling at the back of your knee and are often the result of arthritis or an injury.
- Ganglion cysts — Grow on joints of the hands, feet, wrists, and ankles.
- Ovarian cysts — Form on or inside your ovaries, often during ovulation if they haven’t released an egg. Most ovarian cysts go away without treatment.
What Is an Abscess?
An abscess is a pocket of pus. It forms when white blood cells travel to an infected area of the body to fight the infection. The cells collect within the damaged tissue and form pus, a mixture of living and dead blood cells, germs, and tissue.
An abscess is usually red, warm, and tender to the touch. It may drain if the skin opens and lets the pus out.
Two Types of Abscesses
There are two main types of abscesses.
Skin abscesses
Skin abscesses are easy to spot. They’re usually pink or red, raised from the skin, and painful. Unlike cysts, which are firm, skin abscesses are usually soft, lump-like masses.
Skin abscesses often result from bacteria on your skin. Bacteria normally live on your skin without causing problems. But cuts, scrapes, or ingrown hair follicles can cause infection.
Internal abscesses
Abscesses inside your body occur less frequently than ones on your skin. However, they’re trickier for doctors to diagnose. They often aren’t obvious and, left untreated, can cause damage to internal organs such as your brain and lungs.
Symptoms of an internal abscess depend on what body part it affects. Signs of an abscess may include:
- Chills.
- Diminished appetite.
- Feeling tired for no apparent reason.
- Fever.
- Pain and tenderness in the affected area.
- Sweating.
- Weight loss.
Your doctor may use blood tests and imaging tests to diagnose an internal abscess. These might include:
- CT scans
- MRI
- Ultrasound
- X-rays
Treatment for Cysts and Abscesses
You should see your doctor if you’re unsure if you have a cyst or an abscess, or if it’s bothering you. You should also call your doctor about any lump on your body that doesn’t go away in a couple of weeks.
Treatment for a cyst
Many cysts are harmless and don’t need treatment. But you may want a cyst removed from your face or another visible part of your body if it makes you self-conscious. You should also seek treatment if a cyst is bothersome, like if you have a cyst on your head that you keep scraping with a comb.
Your doctor can drain or remove a cyst on your skin. They’ll use a local anesthetic to numb the area before cutting out the cyst.
Don’t try to remove a cyst yourself. When you leave pieces of a cyst behind, they can form new cysts.
Treatment for an abscess
You should seek treatment for an abscess, both to reduce the pain and to keep the infection from spreading. The treatment will depend on what kind of abscess you have.
Your doctor will drain the abscess to get rid of the pus. You’ll receive pain medication so you don’t feel anything when they drain the abscess. Your doctor may give you antibiotics to treat the infection that caused the abscess.
Removing an internal cyst or abscess
Treatment for an internal cyst or abscess will depend on where it is and your symptoms. You may need a surgical procedure to remove it. Your doctor can talk to you about the best way to proceed.