Several underlying medical conditions can cause a sebaceous cyst, or other epidermoid cysts. These issues range between a variety of different types. Generally, this kind of cyst can grow when, rather than being shed, the surface of the skin goes deeper into the skin. This happens more frequently on certain areas of the body: face, upper back, neck, and others.

Below are some of the potential conditions that are considered to have the potential to lead to sebaceous cysts. Brief details are also mentioned.

Blocked sebaceous gland

These produce sebum, which is actually something that the cyst can become filled with. The sebaceous gland is found just above a hair follicle (mentioned below). Should one become blocked, it can lead to a sebaceous cyst.

Hair follicle damage

The hair follicles are located right below the sebaceous glands. The hairs on the body each grow out of one of these. When the follicle is injured through a wound such as an abrasion, it can end up blocked at the surface.

Ruptured sebaceous gland

Inflammatory conditions can cause a sebaceous gland to be ruptured. Acne is a common cause of this. Some other inflammatory skin diseases include eczema, a condition in which the skin becomes inflamed, itchy and dry, and psoriasis, in which round patches of dry, pink-colored scales form.

Hereditary issues

Different hereditary conditions can bring on sebaceous cysts. One is nevoid basal cell carcinoma syndrome, or NBCCS, which involves defects in multiple systems in the body. Another such condition is Gardner's syndrome, a genetic disorder in which tumors grow outside the colon, and polyps inside of it.

Not having one of these medical conditions does not mean that a patient will not develop a sebaceous cyst, and this list is not an exhaustive collection of possible causes. Additionally, that an individual does have one or more of these issues does not necessarily mean that sebaceous cysts will occur.