A corn is a localised thickening of the cuticle or epidermis (see SKIN) aﬀecting the foot. The thickening is of a conical shape; the point of the cone is directed inwards and is known as the ‘eye’ of the corn. A general thickening over a wider area is called a callosity. Bunion is a condition found over the joint at the base of the big toe, in which not only is there thickening of the skin, but the head of the metatarsal bone also becomes prominent. Hammer-toe is a condition of the second toe, often caused by short boots, in which the toe becomes bent at its two joints in such a way as to resemble a hammer.
Corns and bunions are caused by badly ﬁtting shoes, hence the importance of children and adults wearing properly ﬁtted footwear. Corns can be pared after softening in warm water, or painted with salicylic acid collodion or other proprietary preparations. Bad corns may need treatment by a chiropodist (see CHIROPODY). Bunions may require surgical treatment. Regular foot care is important in patients with DIABETES MELLITUS.