Lobular neoplasia

Although pathologists have recognized the classic forms of lobular neoplasia for decades, our understanding of this disease has changed markedly since its first description. The term lobular neoplasia encompasses a spectrum of entities ranging from atypical lobular hyperplasia to more recently recognized lobular carcinoma in situ (LCIS) variants including LCIS with necrosis and pleomorphic LCIS. Along with an expanded definition of lobular neoplasia, our concept of the pathobiologic potential of these lesions has evolved. While lobular neoplasia has been viewed primarily as a risk marker of invasive breast carcinoma since the late 1970s, there is increasing evidence that they are also non-obligate precursors. In this review, we will address the history of the disease, updated concepts and histologic definitions, and advances in immunohistochemistry and molecular pathology that have shaped both the way we diagnose and manage lobular neoplasia.