Hard bumps on the feet may be caused by physiologic scarring, corns, plantar warts and other skin diseases. 1. physiological scarring: may be due to chronic inflammation or trauma caused by proliferative scarring generally do not need special treatment. 2. corns: mostly seen in adult women, may be due to the foot long-term friction and pressure, resulting in keratin layer hyperplasia caused by, for example, women long-term through the tight shoes or high-heeled shoes, which promotes the formation of corns, manifested in the localization of yellow or yellowish hard bumps. 3. metatarsal warts: a kind of skin proliferation on the toes caused by infection with human papilloma virus. Yellowish or tawny plaques may appear in the pressurized area, which sometimes subside on their own, but may also recur. If you have hard bumps on your feet, if they are accompanied by obvious discomfort and gradually increase in size, you should go to the hospital in time to find out the cause of the bumps and get targeted treatment.