According to the American Cancer Society, breast cancer is the most common cancer diagnosis in women other than skin cancer. The breast is composed of various different tissue components, resulting in a variety of potential histopathological types of cancer. Histopathology is the study of microscopic patterns of disease in body tissues.
Breast Anatomy
The normal breast consists mostly of fat and connective tissue. Admixed glands and lobules are composed of epithelial cells responsible for milk production with pregnancy. Similar cells line interconnecting ducts leading from these glands to the nipple.
Biopsy Diagnosis
A pathologist examines any breast tissue removed at biopsy for the presence or absence of tumor. The growth pattern and appearance of any cancer cells seen under the microscope determine the specific histopathological type of the cancer.
Noninvasive vs. Invasive Cancer
An early stage of breast cancer is classified as noninvasive, or in situ. These cancer cells remain confined within the originating glands or ducts and have not yet extended into surrounding connective tissue. Truly noninvasive cancers do not have the ability to spread to lymph nodes or more distant sites, in contrast to more advanced invasive cancers.
Common Invasive Breast Cancers
The two most common types of invasive breast cancer are ductal carcinoma and lobular carcinoma. According to "Sternberg's Diagnostic Surgical Pathology," ductal carcinoma accounts for 50 to 75 percent of all breast cancers and lobular carcinoma another 10 to 15 percent. Both of these arise from the lining of epithelial cells of the glandular or ductal portions of the breast. Important prognostic features include size of the tumor, degree of cellular abnormalities and how rapidly the tumor cells are multiplying.
Breast Cancer Variants
Less common subtypes of breast cancer also occur, most of which represent variations in cell differentiation or growth pattern of ductal and lobular carcinomas. Mucinous, medullary, papillary and metaplastic carcinomas are examples of these. Inflammatory carcinoma and Paget's disease of the nipple are clinical variants that may be recognized by skin changes seen on physical examination. Some subtypes have a different prognosis from that of common breast cancer. Breast cancer in men is uncommon. According to Breastcancer.org, it represenst less than 1 percent of all breast cancers. Ductal carcinoma is the most common type, and prognosis is similar to that in women when compared by stage.
Non-Epithelial Breast Malignancy
The connective tissues of the breast may also rarely give rise to malignant tumors. Phyllodes tumors consist of both connective tissue and epithelial cell components, either of which may be cancerous. Blood vessel tumors, known as angiosarcomas, are the most common pure connective tissue malignancy. Lymphomas may either arise in or secondarily involve breast tissue.
Significance
The pathology report on a breast cancer should always specify, whenever possible, the histopathological type of tumor found. This information is important in helping the oncologist determine the best treatment plan, in conjunction with tumor grade, stage and results of any additional studies.
References
- American Cancer Society: Breast Cancer: What are the key statistics about breast cancer?
- "Sternberg's Diagnostic Surgical Pathology", Fourth Edition; Stacey E. Mills, Senior Editor; 2004: Section II. Breast (pg 355)
- Breastcancer.org: Male Breast Cancer
