Sebaceous cysts emerge on the most exterior layer of skin, named the epidermis. This is the reason why a sebaceous cyst is also known as a epidermal cyst. The skin contains some glands that produce oil, named sebaceous glands. When these become blocked, a sebaceous cyst forms, which is a sac full of a yellow fatty substance.
Sebaceous cysts appear for various reasons. They can be present since birth but usually form due to blocked hair follicles, skin damage or increased levels of testosterone. These types of cysts are very common, do not evolve into cancer and are not a serious health concern. They look like nodules or lumps under the skin, usually painless.
These very common cysts can appear on any skin area of the body. They are most often found on the torso, trunk, the head, behind the ears or on the neck.
Sebaceous cysts have a soft consistency and are located immediately under the skin. They grow slowly in time and are painless, usually they can be moved when touched. Sometimes a central punctum, or a visible hole, is located in their middle.
If the cysts becomes inflamed and burst, the cheesy substance inside comes out. This is named keratin, a pasty compound that sometimes smells bad.
Sebaceous cysts are normally painless and their size can remain the same in time. However, if the cyst becomes inflamed it can hurt or start to become annoying, especially if it grows in size. Removing the keratin inside the cysts is not a good idea, since pressing it or touching the cysts too often can cause infections. However, sometimes the keratin can burst out on its own.
A sebaceous cyst can be infected if the area gets red or tender. Another symptom of infection is the increased skin temperature in the area of the cyst, with a warm feeling.
Sebaceous glands located in the skin have the role to produce sebum, which is an oily substance required for the maintenance of the skin and hair. Sebaceous cysts appear when the exit duct of the gland becomes blocked and the sebum can't leave. This normally happens because of damage to the area, although other reasons for blocks also exist.
Skin damage can have any causes, such as surgery or wounds. Local conditions like acne can also block the ducts. Since the cysts have a slow rate of growth, they can appear several months after a trauma.
Many other causes for cysts are possible. The skin is sometimes damaged during surgery or the ducts can be deformed or have a bad shape from the start. Sebaceous cysts can also be caused by genetic diseases, such as the basal cell nevus syndrome or the Gardner's syndrome.
Sebaceous cysts are not painful and don't cause any problems if they are small in size. However, large ones become uncomfortable and can be very painful. They can be very difficult to manage if located on the face or the neck.
The substance inside the cysts is actually made of keratin flakes, the main building block of the nails and skin. Keratin is usually hard but cysts tend to be soft when touched.
Sebaceous cysts can be found on every area of the body. The most common locations where they emerge are the face, neck, back and scalp.
Most cysts are harmless and can be ignored. However, there are a number of signs that one of them is dangerous and possibly cancerous. It is unusual if a lump reforms very fast after being removed. Formation of pus, pain or redness are symptoms of infection. If a cyst has a diameter larger than 5 cm, it is another worrying sign.
In most situations, sebaceous cysts are not harmful and heal on their own without any treatment. It is possible however for them to become inflamed, which makes the skin around them very sensitive.
Large size sebaceous cysts can become a problem and hamper movement. In such a case, they can be removed. This is usually done through surgery, there are several procedures available in a doctor's office or hospital.
Injecting steroids into a sebaceous cyst reduces its size and the associated pain. This is often the chosen procedure for inflamed cysts. If one becomes infected, a surgical incision might be required to drain the pus inside it. Infected sebaceous cysts are sometimes very painful, so a local anesthetic must be injected to numb the area around them. Afterwards, the cyst can be drained safely.
It is important to treat sebaceous cysts in order to avoid complications. If ignored, the infection can expand through the skin layers. This condition is known as cellulitis and is a more widespread form of infection that requires incision, drainage and a cure with oral antibiotics.
Sebaceous cysts can also be removed completely, by extracting not only their content but also the walls. In order to decrease the risk of a cyst developing again in the same location, doctors usually perform this procedure only when no infection or inflammation is present.
If a sebaceous cyst is not removed through surgery and is only drained, there is a high chance for it to grow back. Some patients refuse it because scars can develop, but surgery is by far the best clinical option of treatment for this condition. However, since sebaceous cysts are not a serious health problem, doctors usually allow their patients to choose from the available treatment options.
The most common way to remove a sebaceous cyst is the so-called wide excision, a classic surgical procedure. This is very effective but a visible long scar can remain in the area. A more limited excision leaves a small scar but the risk of a cyst recurrence is higher. A modern treatment option is the punch biopsy excision done with a laser. The focused beam of light creates a hole used to drain the cyst core, while the walls are eliminated after about a month.
Doctors sometimes prescribe the application of an external product with antibiotics in order to decrease the risk of infection in the area. After the wound is completely healed, there is no need for antibiotic. Scar creams can reduce the risk of post-surgical scars.