Callosities and corns are caused by pressure and friction due to faulty weight-bearing, orthopedic deformities, improperly fitting shoes, or neuropathies.
Tenderness on pressure and “after-pain” are the only symptoms. The hyperkeratotic well-localized overgrowths always occur at pressure points. Dermatoglyphics (fingerprint lines) are preserved over the surface (not so in warts). When the surface is shaved with a 15 blade, a glassy core is found (which differentiates them from plantar warts, which have multiple capillary bleeding points or black dots when pared).
Treatment consists of correcting mechanical abnormalities that cause friction and pressure. Callosities may be removed by careful paring of the callus after a warm water soak or with keratolytic agents as found in various brands of corn pads.
Plantar hyperkeratosis of the heels can be treated successfully by using 20% urea (Ureacin 20) or 12% lactic acid (Amlactin) or combinations nightly and a pumice stone after soaking in water.
Callosities on diabetic feet, especially in the setting of hyposensate neuropathy, can be a major problem and the value of early podiatric management to prevent complications is very high.
et al. Pathogenesis and treatment of callus in the diabetic foot. Curr Diabetes Rev. 2016;12(3):179–83.