[Ductal hyperplasia and ductal carcinoma in situ. Definition--classification--differential diagnosis].

This review emphasizes the pathology of premalignant ductal breast diseases and its practical relevance to the patients management. The histological criteria for recognizing Ductal Hyperplasia (DH) are now well established. These include an intraluminal heterogeneous proliferation of glandular cells positive for keratins 8/18/19 and epithelial cells with expression of keratins 5/6/14. As a hyperplastic process the epithelial cells disclose an haphazard irregular growth with slit like irregular lumina (fenestrated growth pattern). The florid DH indicates a slight subsequent increased risk for cancer development. Our knowledge of the nature of noninvasive ductal neoplasia continues to evolve. Recent molecular genetic and immunohistochemical efforts have disclosed that atypical ductal hyperplasia (ADH) constituted a clonal neoplastic proliferation of an epithelial cell. Histological hallmarks of ADH are their cytologic features of uniformity and monotony of proliferation of cells and its micropapillary, cibriform or solid growth pattern. So from histology ADH simulates the highly differentiated DCIS, but can be distinguished from the latter quantitatively by the aggregate cross sectional diameter or the number of ducts that are completely involved by the atypical proliferation. ADH indicates a few fold subsequent increased risk for developing carcinoma. So this lesion requires a close follow up with 3 to 4 examinations per year and annual mammograms. Ductal carcinoma in situ (DCIS) consists of cytologically malignant cells in the parenchyma that have not invaded into the stroma. Recent studies have shown that DCIS is a heterogeneous group of tumors. Attempts have been made to classify it into histologic patterns, nuclear grades, tumors with or without comedo-necroses etc. We can draw the conclusion from several studies that the most important histologic feature is the nuclear grade. Holland et al. have suggested a very useful classification scheme that includes nuclear grade and histological features. The modifiers of treatment are as follows: 1. nuclear grade or differentiation of the DCIS 2. extension of the lesion 3. excision with clear margins So efforts to classify DCIS underscore the central role of pathology in determining the grade of the DCIS, its size and the adequacy of the surgical excision in terms of free margins. All three parameters are included in a score system of the Van Nuys Prognostic Index.