Each breast contains glandular tissue: lobules, which contain cells that produce breast milk; and ducts that carry that milk to the nipple. The nipple itself also contains a small amount of ductal glandular tissue, as well as muscle cells, nerves and overlying skin. Although the majority of breast cancers occur in the breast outside the nipple, a number of cancers can affect the nipple itself.
Paget's Disease
Paget's disease, a form of cancer characterized by the presence of cancerous Paget cells, commonly affects the nipple. The National Cancer Institute indicates that although Paget's disease is a distinct form of cancer, it occurs in combination with other forms of breast cancer in 95 percent of cases. The majority of women diagnosed with Paget's disease are over the age of 50, but the disease can rarely affect women as young as in their 20s. Paget's disease leads to skin abnormalities of the nipple, with many patients with this form of cancer suffering from red, scaly and painful skin on the nipple. Patients with Paget's disease commonly undergo surgery to remove the nipple and any other affected breast tissue. In rare cases, patients with Paget's disease must also undergo other treatments such as drug therapy.
Ductal Carcinoma in Situ
Since the nipple contains a small amount of duct tissue, ductal breast cancers can occasionally occur in the nipple. A report published in the "International Journal of Surgical Pathology" in 2009 describes the presence of ductal carcinoma in situ, or DCIS, in the nipple. DCIS is a relatively non-invasive cancer of the ducts that can eventually turn into more severe breast cancer. The study indicates that the patient developed ductal cancer at the very tip of the nipple, leaving the rest of the nipple free of disease. The authors of the study highlight the importance of searching for ductal carcinoma in all regions of the nipple, since any cancer cells colonizing in the nipple can lead to more advanced cancer development.
Invasive Ductal Carcinoma
Other forms of ductal cancer, like invasive ductal carcinoma, or IDC, can also occur in the nipple. IDC is a more aggressive form of ductal breast cancer, with a high potential to develop into metastatic breast cancer. Like DCIS, IDC can occur in the nipple due to presence of small amounts of ductal tissue. A study published in "Breast Cancer" in 2007 describes the case of a woman with IDC of the nipple. The woman developed a mass protruding from her nipple, as well as additional masses within her breast. The study indicates that IDC in the nipple can be treated with a mastectomy to surgically remove the affected breast, including any cancer cells growing in the breast tissue.
