Hyperkeratosis, or commonly referred to as callus, is the result of increased thickness of a layer of the skin called the stratum corneum. Calluses are often found at sites of increased pressure, increasing the blood supply and nerve stimulation at the site. This increases cell production beyond what is needed, leading to these areas of thick skin.

Fissures, or commonly referred to as cracked heels, are cracks in the topmost layer of the skin called the epidermis. Fissures are the result of loss of elasticity or hydration in the skin, causing it to split open. Fissures may become more painful as they go deeper into the skin, and may cause bleeding. If left untreated, it is possible to get an infection.