Sebaceous cysts are sacs just beneath the skin that are filled with an oily, white, semisolid material called sebum. If the sebum becomes infected, the cyst will be red and painful. Sebaceous cysts are commonly seen on the scalp, labia, scrotum, chest, and back, but can be found anywhere on the body.

What is going on in the body?

Sebaceous cysts tend to develop in teenagers because of an interaction among hormones, sebum, and bacteria. During puberty, the glands in the skin produce excessive sebum. In skin that is prone to acne, the sebum and dead skin cells clog the hair follicles and form comedones, or clogged pores. A comedone may break through the pore wall underneath the skin and release its contents. This causes a pimple or pustule. If this substance is released deep into the skin it will cause a sebaceous cyst.

What are the causes and risks of the condition?

There is no known cause for sebaceous cysts. Acne, which leads to sebaceous cysts in some individuals, is caused by four factors:

Virtually every adolescent experiences some comedones, or clogged pores. Generally, acne starts around the age of 10 to 13 years and lasts 5 to 10 years. Around the age of 14 or 15 years, approximately 40% of adolescents have acne that is serious enough to require a visit a healthcare provider. Acne happens in both male and female adolescents, but males are more likely to have a severe form of acne. Some people develop acne for the first time as an adult.

Certain forms of acne tend to run in families. If an adolescent's parents or older siblings have severe acne, the adolescent has a higher risk of developing severe acne. Acne is more common in Caucasian Americans than in African Americans or people of Asian descent.

Risk factors that increase an individual's risk for development or worsening of acne include the following: