blood vessels which feed the skin, thickening of the skin with callus increases the difficulty of supplying nutrients to the skin. Callus formation is seen in high numbers of patients with diabetes, and together with absent foot pulses and formation of hammer toe, this may be an early sign of individuals at an increased risk for foot ulcers. The stiffness of a callus or corn, coupled with the shear and pressure that caused it, may tear the capillaries or adjoining tissue, causing bleeding within the callus or corn. This can often be result of trying to pick, cut, or shave off the callus by yourself at home. Although the bleeding can be small, sometimes small pools of blood or hematoma are formed. The blood itself is an irritant, a foreign body within the callus that makes the area burn or itch. If the pool of blood is exposed to the outside, infection may follow. Infection may also lead to ulceration. This process can be prevented at several places. Diabetic foot infections are the leading cause of diabetic limb amputation. Society and culture Calluses in the hands are frequently associated with manual labor and blue-collar workers. During the Gads Hill Train Robbery in 1874, the James–Younger Gang purportedly refrained from robbing men with calloused hands, assuming them to be working class laborers. Such notion is also present in Māori culture, where the words raupā and raupo refer to hands left cracked and chapped due to manual work, and are used as similes for someone deemed a hard worker. Calluses have also been known to develop on the forehead from the frequent prostrations required in Muslim prayer; known as a prayer bump or zebiba, such calluses are considered marks of piety in some Muslim countries, and people have been known to take special steps, such as praying on straw mats, to encourage the callus to develop. Calluses may also form on the fingertips from the repeated pressure and friction of playing stringed instruments. This formation of calluses allows the player to repeatedly depress the strings without causing pain. Because of this, callus formation is viewed as something of a rite of passage for beginner string players. See also Hyperkeratosis Callosity Catagmatic References Further reading Taber's Cyclopedic Medical Dictionary, 15th Edition, CL Thomas, M.D., M.P.H., editor, F.A. Davis Company, Philadelphia, PA, 1985. The Merck Manual of Medical Information, Home Edition, R Berkow, M.D.,