Paget's disease of the nipple is an uncommon and not fully understood type of cancer that forms in or around the nipple and accounts for about 1% of all breast cancers. Scientists theorize that the disease either starts in the skin or in the breast and spreads into the nipple. Symptoms may include redness or crusting of the nipple skin, tingling, itching, increased sensitivity, burning, or pain in the nipple. Paget's disease of the nipple is diagnosed by performing a biopsy. Mastectomy is the usual treatment, and radiation and chemotherapy may be recommended.