*-Introduction: Ductal Carcinoma in situ

Human mammary tissue. Duct (D) and lobules (L1, L2, L3, L4). The extralobular terminal duct (ETD) connects the terminal acini (or ductules) to the duct. Together the lobule and ETD make up the Terminal ductal lobular unit. Most major breast lesions arise from the TDLU, including: ductal carcinoma in situ (DCIS), lobular carcinoma in situ, fibroadenoma and fibrocystic disease, like cysts, apocine metaplasia, adenosis and epitheliosis. http://mammary.nih.gov/atlas/histology/Wellings001/Srwtxt/index.htm

The term "carcinoma in situ" refers to cancer cells confined to the tissue where it developed. Ductal Carcinoma in situ (DCIS) consists of abnormal cells confined to the milk ducts of the breast. These cells have the microscopic appearance of cancer cells but have not yet obtained the ability escape into other tissue.

Unlike typical breast cancer, 95% of DCIS cases do not form palpable lesions, or "lumps." Therefore, DCIS is rarely detected by manual breast examination. The majority of DCIS cases are diagnosed on routine mammograms.

Ductal carcinoma in situ is a relatively new diagnosis. Mammography has proven to be an important tool in the diagnosis of DCIS. Microcalcifications, resulting from necrosis of DCIS cells within the ducts, are often visible on mammograms. Consequently, diagnoses of DCIS have increased, as the number of women receiving yearly mammograms has increased.

The National Institutes of Health estimate that more than 62,000 new cases of DCIS will be have been diagnosed in 2009. DCIS accounts for 20-25% of all new cases of breast cancer. Approximately 80-85% of DCIS is diagnosed by mammography. DCIS usually appears on mammography as linear or multiple clusters of fine granular calcifications with a branching-type pattern. Unfortunately mammography cannot differentiate DCIS cases which will become invasive. Diagnosis is usually confirmed with a core biopsy or needle localization/excisional biopsy.

The rate of DCIS is comparable among women of different ethnicities. Risk factors for DCIS and invasive breast cancer are similar, suggesting a common etiology for both diseases.