Intraductal Proliferations (DCIS, ADH, and UDH)

Abstract

The diagnostic evaluation of intraductal proliferations, including ductal carcinoma in situ (DCIS), atypical ductal hyperplasia (ADH), and usual ductal hyperplasia (UDH) is one of the most common diagnostic challenges in breast pathology. While proliferations on the ends of this diagnostic spectrum (high-grade DCIS and classic usual ductal hyperplasia) are usually more straightforward to classify, the distinction between low-grade DCIS and ADH can be particularly problematic. An understanding of the biology of these lesions reveals more about their complexity and which lesions are more closely related to each other. When evaluating intraductal proliferations on core needle biopsy samples, pathologists should understand the critical aspects of establishing these diagnoses as well as their clinical impact. This chapter will review practical approaches to the diagnosis of intraductal proliferative lesions on core biopsy as well as some of their diagnostic challenges and clinical implications.