Update on atypical epithelial hyperplasia and ductal carcinoma in situ.

Atypical ductal hyperplasia (ADH) as an indicator of increased risk for developing breast cancer is well established. Refinement in its molecular characterisation, especially as it relates to risk, continues to be challenging, largely because of its small and very focal nature. Also a challenge is appropriate management of ADH when present on core biopsy. Additional support for ductal carcinoma in situ (DCIS) as a precursor to invasive cancer, as well as recent molecular characterisation of DCIS are presented. The importance of margin assessment in cases of DCIS and the limited role for sentinel lymph node biopsy in this setting are reviewed.