•  This is a view of a single duct containing intraductal carcinoma.

•  The duct has been filled in by cells which appear in the section to be a monolayer with a few round holes (white arrows) in it.

•  The cells show no orientation to the "holes".

•  The cells are confined by a basement membrane (black arrows) to the duct.

• Unknown

• Some evidence that BRCA1 abnormalities already present in in situ disease

• See discussion of infilatrating duct carcinoma for more details.

• Increasing age

• More frequent in women of low parity with first child after 30

• Increased in obesity

• Increased in women with history of atypical hyperplasia

• Increased in women with history of breast carcinoma

• Increased in women with mother or sibling with breast cancer

• Increased relative risk of breast cancer 10 fold

• Lesions are generally extirpated surgically with clear margins, followed by radiation therapy, or by mastectomy

• For more information on prognosis and treatment, consult NCI web site.
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• May be associated with microcalcifications within the lumens

• Gross findings may be of fibrocystic change

• May form mass

• In comedo variant cysts (dilated ducts) are filled with granular, yellow white material

• May be associated with invasive carcinoma

• There are several varieties including papillary (delicate fibrovascular cores covered with atypical cells), cribriform (multiple lumens within a single duct), solid, micropapillary (tiny epithelial papillae), comedo (around necrotic center) and clinging in which only one to two abnormal cell layers "cling" to the basement membrane.

• All show loss of typical bilayered epithelium

• All show enlarged round to oval nuclei with nucleoli; comedo variety typically shows nuclear pleomorphism, hyperchromasia, large nucleoli and mitotic activity

• All show loss of polarity towards lumen

• All types may show intraluminal microcalcifications

• Current literature from PubMed at National Library of Medicine