Each breast contains specialized tissues that facilitate breast milk production and lactation. Milk is produced in bulb-like cellular structures within the breast lobules, then travels along the ducts to the nipple, where it is expelled from the body. Several ducts and lobules form a tree-like structure within each breast, surrounded by other tissues like fat cells and blood vessels. Breast cancer can form in a number of locations within the breast, leading to distinct symptoms.
Ductal Lumps
The most common site of breast cancer growth is within the ducts of the breast--ductal breast cancer accounts for around 80 percent of total breast cancer cases, reports BreastCancer.org. During ductal breast cancer development, duct cells begin to proliferate out of control, blocking the ducts and forming a dense growth within one duct. The result is the growth of a palpable lump that remains fixed in one area of the breast and feels firm to the touch. Ductal breast cancers are often palpable during a breast self-examination or a clinical exam, and can be spotted on a mammogram. Once diagnosed, surgery, radiation therapy, hormone therapy or chemotherapy can treat the ductal cancer.
Lobular Lumps
Another possible site of breast cancer is within the breast lobule, with invasive lobular cancer account for around 10 percent of breast cancers, according to BreastCancer.org. Each lobule contains a number of structures called acini, made up of bulbs of cells. Lobular cancer cells begin to proliferate rapidly and disrupt the normal structure of the lobule, leading to the development of a breast growth. While ductal breast cancers feel like a distinct lump, lobular breast cancers feel like a thickening of part of the breast tissue. The lump from a lobular carcinoma may not have distinct borders, but generally feels firm to the touch. A lobular carcinoma is typically detectable on a mammogram, and treatment for this cancer may involve a mastectomy, chemotherapy or radiation therapy.
Nipple Cancer
Cancer of the nipple, called Paget's disease, is a rare but aggressive form of breast cancer. Paget's disease involves the formation of cancerous Paget cells within the nipple, and almost always occurs in combination with other cancers, like ductal carcinoma, according to the National Cancer Society. As a result, patients with Paget's disease may often develop defined breast lumps during cancer development, along with symptoms in the nipple like skin rashes, redness and scaly or flaky breast skin. Since Paget's disease is so aggressive, treatment for this form of cancer typically requires a complete removal of the breast tissue, along with chemotherapy or radiation therapy to kill any remaining cancer cells.
