Epidermal cysts are yellow to gray, smooth, dome-shaped nodules with a central punctum and contain keratin. Epidermal cysts vary in size. Lesions of this size will show little tendency to rupture.

Spontaneous rupture of the wall results in discharge of a soft yellow keratin into the dermis. A tremendous inflammatory response ensues and the cyst becomes red, swollen and tender.

Epidermal cysts occur commonly on the back of the ear and may become clustered. Posterior neck and back are also common sites.