A sebaceous cyst is an umbrella term for epidermoid and pilar cysts. It means a fluid-filled sac or lump and either originates from skin cells (epidermoid) or from a hair follicle (pilar). Sebaceous cysts are not harmful and can slowly get bigger over time or can disappear without any treatment. They are non-cancerous, so they will not cause harm or spread to any other part of your body, and they do not usually require treatment.
They appear as round, mobile lumps that can feel bouncy and can at times release a white or yellow paste-like substance from the inside of it if there is a break in the lining of the cyst and it is squeezed.
We do not recommend squeezing cysts as they can cause inflammation or even infection.
Sebaceous cysts are not painful unless they become inflamed or infected.
Sebaceous cysts are common and can occur in anyone.
Epidermoid cysts originate from the cells of the outermost layer of the skin, known as the epidermis. Epidermoid cysts are more common in young adults and people with acne, whereas pilar cysts are more common in middle-aged females and you may be more likely to develop a pilar cyst if someone in your family has had them. You tend to find epidermoid cysts on the upper body or around the genitals and for pilar cysts, they tend to be on the head, in amongst your hair. They appear as small, firm bumps beneath the skin, often with a smooth surface and a central punctum. Epidermoid cysts grow slowly and are generally non-cancerous. Commonly found on the face, neck, chest, and back, they are usually painless, although they can become tender if they become infected. Treatment, if necessary, may involve drainage or surgical removal by a healthcare professional.
Pilar cysts, also known as trichilemmal cysts, arise from the hair follicles, specifically the outer root sheath (trichilemma) of the hair follicle. Similar to epidermoid cysts, they contain keratin. Pilar cysts are round, smooth, and mobile lumps beneath the skin, often feeling like small, firm balls. They tend to grow slowly and are generally benign. While commonly found on the scalp, they can also appear on other areas of the body. Pilar cysts are usually painless unless they become infected or inflamed.
Sebaceous cysts are not contagious and cannot be passed on to others.
You should see your doctor if you develop a lump that you suspect to be a sebaceous cyst, this is so that your doctor can confirm it is a sebaceous cyst as there are many other causes of lumps with a small number of these being serious. You should also see your doctor if you have a diagnosed sebaceous cyst but it has grown quickly, has become painful or hot, or it has changed significantly in any way.
They will also ask you about your medical history and any relevant family medical history. They will then examine the lump and if necessary send you for further investigations such as a scan if they want to check the diagnosis. If a sebaceous cyst is confirmed and it is small, you will not usually require any treatment. If the cyst is infected (hot, painful and red) you will likely be given a course of antibiotics to take.
Sebaceous cysts are not considered serious, so they are not usually removed on the NHS, unless certain criteria apply. You can choose to have it removed privately, and this is a simple procedure by a dermatologist or plastic surgeon.
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