A sebaceous cyst is a type of closed cyst that lies beneath the outside of the skin. This kind of sac fills with a fatty material called sebum (which has been produced by the sebaceous glands in the epidermis). Some people consider a sebaceous cyst to be defined not by its content, but rather by the fact that it came from the sebaceous glands. Also, some consider the epidermoid cyst to be equal or at least similar to the type being discussed here.

Symptoms

A sebaceous cyst may appear on nearly any part of the body, aside from the soles (feet) and the palms (hands). Several of the common locations for these to occur are: face, scalp, ears, upper arm, chest (in males), and back. Generally, they occur more frequently in areas with more hair.

Some other characteristics or symptoms of this condition may include: smooth feeling, round shape-wise, sizes may differ, containing moveable contents (fibrous fluids, keratinous material, fluids containing pus and blood, etc.). The presentation and contents of a sebaceous cyst may vary, in particular due to infection or a lack of one.

View more related to potential symptoms and appearances.

Causes

Some potential sebaceous cyst causes include the following items (may include rare medical causes):

Nevoid basal cell carcinoma syndrome (shortened as NBCCS)
Blocked sebaceous glands
Dermatobia hominis (human botfly)
Excessive production of testosterone
Gardner's syndrome (type of autosomal dormant polyposis)
Swollen hair follicles

Continue reading about possible sebaceous cyst causes.

Diagnosis

Sebaceous cyst diagnosis is made by a doctor or other medical professional. Often, they are diagnosed by examination by the doctor. At times, a biopsy may be taken in order to rule out potential differential diagnoses of conditions with similar appearances.

Treatment

After the diagnosis has taken place, a treatment method may begin. If one of these continues to expand it may lead to infection or other unwanted effects, so in some cases treatment may be recommended even though it is not always required. Sebaceous cyst treatment options include both surgical and non-surgical. If the cyst has already become infected, it may require additional treatment (such as antibiotics). The patient should not attempt to break or pop one, as this could lead to infection in the nearby tissue.