Cytology of “Significant” Breast Ductal Proliferations

OBJECTIVE: To determine the usefulness of fine needle aspiration cytology in diagnosing breast ductal proliferations that fall short of invasive cancer (hyperplasia, atypia and in situ carcinoma). STUDY DESIGN: This study was a comparison of the cytomorphology and histomorphology of 30 palpable breast lesions in which an initial fine needle aspiration diagnosis of ductal hyperplasia or atypia was based on available criteria. RESULTS: Among six patients, a cytologic diagnosis of mild hyperplasia, based on monolayered cell sheets, was confirmed in five. Fourteen cytologic reports of moderate hyperplasia, based on three-dimensional cell clusters, cell overlap and sublumens, were confirmed in 12. A cytomorphologic diagnosis of atypical ductal hyperplasia was rejected in four of seven patients. Three cases of marked cytologic atypia were diagnosed histopathologically as ductal carcinoma in situ. CONCLUSION: In breast aspirates, three-dimensional ductal cell clusters, a swirling pattern of growth, sublumens, cell dyscohesion and conspicuous nuclear overlap indicate moderate ductal hyperplasia. Ductal atypia should be diagnosed only on such nuclear features as anisonucleosis, irregular nuclear membranes, clumped chromatin and eosinophilic macronucleoli. Cytologists should highlight those features which are important to diagnose breast proliferations as significant from the viewpoint of progressing to invasive cancer and not attempt too fine a classification of these lesions.