Breast malignant, males, children
In situ carcinoma
Ductal intraepithelial neoplasia (DIN)

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 18 October 2016, last major update January 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Ductal intraepithelial neoplasia [title]

Cite this page: Ductal intraepithelial neoplasia (DIN). website. Accessed November 22nd, 2017.
  • This terminology avoids use of “carcinoma”, but is not widely used
  • Proponents claim it reduces the “artificial separation” between ADH and low grade DCIS (Virchows Arch 2006;449:609)
  • If DIN terminology is used in a report, recommended to also reference traditional terminology
Microscopic (histologic) description
  • Most invasive breast cancer cases are associated with more than one type of DIN
  • Morphologic subtypes:
    • Solid
    • Cribriform
    • Comedo
    • Micropapillary
    • Papillary
    • Flat

  • Grades:
    • UDH: usual ductal hyperplasia
    • DIN 1A: flat epithelial atypia
    • DIN 1B: atypical ductal hyperplasia
    • DIN 1C: DCIS grade 1 (low grade)
    • DIN2: DCIS grade 2 (intermediate grade)
    • DIN3: DCIS grade 3 (high grade)
  • Source: Tavassoli: Tumours of the Breast and Female Genital Organs, WHO, 2003

  • Initial version as proposed by Tavassoli is below (Mod Pathol 1998;11:140), but was subsequently modified to above:
    • DIN 1a: usual ductal hyperplasia
    • Din 1b: flat epithelial atypia
    • Din 1c: ADH and small grade I DCIS
    • DIN 2: large grade I and grade II DCIS
    • DIN 3: grade III DCIS
Additional references