Ductal cancer has a pre-invasive stage known as breast ductal carcinoma in situ. Once the cancer cells invade the basement membrane of the breast and penetrate the underlying supportive tissue, it is then called invasive ductal cancer. These cancers often lead to the formation of fibrous tissue within the breast that shows on a mammogram with stellate structure. Once large enough to be felt on palpation, a lump of this origin is quite firm in relation to the surrounding breast tissue.
Lobular cancer is often termed “infiltrating” lobular cancer because the cancer cells infiltrate the supporting tissue in a linear fashion. Cancer cells appear as interspersed cords among normal breast tissue, making both mammographic diagnosis and detection by palpation more difficult. The association of infiltrating lobular cancer with a change in the terminal lobular units of the breast duct characterized by atypical lobular cells thought to be the pre-invasive phase of infiltrating lobular cancer. This proliferation of cells was called lobular carcinoma in situ and seemed to be similar to ductal carcinoma in situ in invasive ductal cancer. With more studies, it was found that lobular carcinoma in situ was not necessarily a malignant transformation and when found by itself in a breast biopsy, it did not go on to give rise to an infiltrating lobular carcinoma in most cases. Its presence did, however, may lead to believe that the breast tissue was more prone to cancer of both ductal and lobular types and this increased risk was to two to three times the average woman’s risk.
Mucinous or colloid breast cancer accounts for five percent or less of breast malignancies. In this type, the cancer cells retain the ability to secrete mucin, a liquid material that accumulates within the cells. This type of cancer has a good prognosis and is not prone to spread to the lymph nodes and blood system.
Papillary breast cancer is quite rare and under microscopic examination of cancer tissue, the cells form patterns that look like fern rods. The invasive form of this type of cancer is well differentiated and has a good prognosis. Since papillary cancers tend to have a central localization in the breast, often behind the nipple, local control without deformity can be difficult.
The inflammatory type of breast cancer involves a high-grade cancer cell of ductal origin that has a high propensity to spread to the lymph vessels, especially those just beneath the skin. Often, there is no mass or lump upon palpation, but swelling and redness is visible resembling an infection – thus the name inflammatory breast cancer. The treatment protocol usually involves a trial of antibiotics without a response followed by a skin biopsy that will reveal cancer cells in the dermal lymph vessels. This type of breast cancer is very aggressive and surgical removal will not be able to control it locally. However, treatment has evolved that has substantially improved the outlook for women with inflammatory breast cancer. Chemotherapy given as an initial treatment often dramatically changes the breast to a normal appearance, then making local control with surgery and radiotherapy feasible.
There are very, very rare malignancies of the breast that originate form the lymph (lymphoma), or from fat (liposarcoma), or from the skin or its glands. These account for less than a fraction of one percent of all breast cancers.