Atypia in breast fine-needle aspiration smears correlates poorly with the presence of a prognostically significant proliferative lesion of ductal epithelium.

Proliferative lesions of breast duct epithelium are associated with an increased risk of subsequent carcinoma. Fine-needle aspiration criteria for these lesions are poorly defined; most studies are retrospective and do not clearly use the classification of Page and Rogers. Suggested criteria for "atypia" include crowded, enlarged, overlapping nuclei in three-dimensional groups or sheets, loss of cohesion, occasional single cells, a homogeneous cell population, chromatin changes, and increased cellularity in older patients. Our prospective series of 1,925 aspirations included 717 breast cases, of which 25 (3.5%) were considered sufficiently atypical to possibly represent proliferative lesions, but were not suspicious for carcinoma. Fifteen patients with histologic follow-up formed the basis for this study. All had physical examinations and mammogram results consistent with fibrocystic change. Their ages ranged from 30 to 70 years (median age, 44 years). Cytologic changes of atypia were cataloged. Histologically, six cases (40%) showed prognostically significant lesions (moderate, florid, or atypical hyperplasia and one lobular carcinoma in situ). Many (60%) cytologically provocative lesions may originate in prognostically trivial lesions. At this time our limited understanding of the cytologic presentation of these lesions indicates that surgical excision is essential in all instances. Efforts to recognize and properly classify these proliferations in cytologic material should continue.