A hard bump on the foot may be associated with metatarsal warts, calluses, corns, and exophytic bone warts. 1. Metatarsal warts are a skin disease caused by infection with the human papilloma virus, mainly manifested as keratinized pimples on the soles of the feet and the front of the metatarsals that appear slightly above the skin surface. 2. Callus is due to excessive pressure and the formation of a kind of hyperplasia, hyperplasia within the stratum corneum without blood vessels and nerve distribution, so usually no pain. 3. Chicken eye is due to the local skin for a long time by extrusion or friction and the formation of a kind of keratin hyperplasia, the center part of the pressure will appear after the pain and discomfort. 4. Ectodermal warts are a kind of solitary osteochondroma, belonging to a kind of bone tumor. The main manifestation of the gradual increase of hard lumps, when the tumor further increase will cause compression and pain and cause joint movement disorder, and so on. Due to the relatively large number of causes, it is necessary to consult a doctor for specific cases.