Many people often call their lumps under their skin “sebaceous cysts.” But these most often are “epidermoid cysts.” Sebaceous cysts are less common and they affect the sebaceous glands, the skin oil glands.

Epidermoid cysts are made up of  keratin and fat. They appear usually on the neck, face and upper body. They appear for many reasons, often because of an acne or skin injury. They are less common in woman than in man.