Epidermoid cysts are small, benign lumps that form beneath the skin. They occur when skin cells multiply and become trapped, creating a sac filled with a thick, yellowish substance called keratin. These cysts can appear anywhere on the body but are most commonly found on the face, neck, and trunk. While epidermoid cysts are usually harmless and painless, they can become inflamed or infected. Treatment options include drainage or surgical removal if necessary. They are different from sebaceous cysts, which are often confused with them, as sebaceous cysts arise from oil glands.