What are Epidermal inclusion cysts (EIC)?
Epidermal Inclusion cysts are the most common type of skin cyst. They are often incorrectly called sebaceous cysts, but they do not arise from sebaceous (oil) glands, but instead from the skin of a hair follicle. They are non-cancerous, not contagious and sometimes can go away on their own. Occasionally they become infected or inflamed. They can occur anywhere on the body, but are often found on the head, neck, chest and back. They tend to be small nodules that grow slowly, may shrink and grow again, but usually cause no pain or require treatment.
Epidermal cysts are more common in young and middle-aged men, but are also seen in women. They are often skin colored, and of various sizes with a central pore. They are filled with cheesy white substance called keratin, are soft and smell bad. If the cyst is filled with pus it is called an abscess.
They are caused by an accumulation of trapped keratin, a protein that naturally exists inside skin cells, where the skin has been damaged or an inflamed hair follicle; and are often found in conjunction with acne. If there are many of these cysts the cause could be a genetic illness.
How are EICs diagnosed and treated?
Epidemal inclusion cysts can be diagnosed by clinical examination based on the appearance of the cyst. Treatment is not needed, unless the cyst is bothersome, or frequently drains, becomes inflamed, or infected. Injection of steroid solution or oral antibiotics can be used to calm inflammation or infection. Sometimes cysts are drained in the office, but surgical removal is the standard treatment for definitive removal.