• The typical appearance is usually enough for confirming diagnosis by observing the characteristic changes in the skin.
• One can diagnose a corn or callus by its looks alone. A callus is hard, dry, and thick. It may feel bumpy and appear grayish or yellowish. It may be less sensitive to touch than the surrounding skin.
• A hard corn is also firm and thick with a soft yellow ring and gray center. A soft corn looks like an open sore.
• Rarely, a skin biopsy may be necessary to exclude other similar conditions.
• Radiographic studies such as X-rays can be used to detect any underlying bony abnormalities that cause abnormal pressure on the overlying skin. For this purpose, a plain x-ray is usually enough, but rarely CT scanning may be necessary.