NCI Definition: A breast lesion characterized by the presence of dilated terminal ductal lobular units in which the epithelial lining has been replaced by a single layer of mildly atypical cells, or there is atypical, monotonous epithelial hyperplasia of three to five layers. This lesion relates to columnar cell change with atypia and columnar cell hyperplasia with atypia. [1]

Disease Details

Flat Ductal Epithelial Atypia, Clinging Carcinoma, Flat Epithelial Atypia, Ductal Intraepithelial Neoplasia, Grade 1A, FEA, Flat Epithelial Atypia of the Breast, DIN 1A
Breast Intraductal Proliferative Lesion


1. National Cancer Institute. NCI Thesaurus Version 18.11d. https://ncit.nci.nih.gov/ncitbrowser/ [2018-08-28]. [2018-09-21].

2. The AACR Project GENIE Consortium. AACR Project GENIE: powering precision medicine through an international consortium. Cancer Discovery. 2017;7(8):818-831. Dataset Version 8. This dataset does not represent the totality of the genetic landscape; see paper for more information.

3. All assertions and clinical trial landscape data are curated from primary sources. You can read more about the curation process here.