ABSTRACT
The separation of specifically defined atypical ductal hyperplasia from smaller examples of DCIS is central to our evolution of understanding of minimal examples of DCIS. Despite some histologic similarities, atypical ductal hyperplasia (ADH) describes a totally different natural history, implicating a moderate increase in risk of later invasive breast cancer anywhere in either breast, importantly initially derived from this same cohort of women [2,3] (see also Paper 10 in this chapter).
