The doctor will examine the skin where a corn or callus has formed. Diagnosis is based on symptoms and visual observation of the corn or callus. They are easily distinguished by:
- Location—Corns usually only form on or between the toes.
- Degree of pain—Corns are usually quite painful, while calluses are usually painless or only slightly painful.
In order to distinguish a corn or callus from a wart , a doctor may pare the lesion with a sterile scalpel blade. Paring of a callus reveals layers of yellowish keratin; paring of a corn reveals a central translucent whitish yellow core, as opposed to the thrombosed capillaries and multiple bleeding points seen in a wart.