The spectrum of cytologic features in nonproliferative breast lesions

The reliability of cytologic criteria to classify nonproliferative breast lesions (NPBL) is still debated. Sampling error and heterogeneity of breast lesions complicates the histologic correlation of fine-needle aspiration results further.

To provide optimal cytohistologic correlation, two smears (one that was stained with hematoxylin and eosin and one that was stained with Diff-Quik [American Scientific Products, McGraw Park, IL]) were prepared from specific tissue sections from breast biopsies without mass lesions. The 42 cases classified as NPBL histologically were included in the current study. The cytologic features of the smears were evaluated.

Cellularity ranged from low (40% of cases) to moderate (50% of cases) to high (7% of cases). The cells were arranged in small clusters in 79% of cases, were mixed with large sheets in 17% of cases, and were in large sheets in 2% of cases. Intact lobules were noted in 31%. The configuration of the epithelial groups was complex in 62% of cases. Myoepithelial cells in the background and within the epithelial groups were noted in all the specimens. The percentage of single epithelial cells was < 10 in 38% of cases, 10-20 in 41%, and 20-30 in 19%. Mild nuclear enlargement and overlap, micronucleoli, and mild chromatin clumping were noted in a significant number of cases.

NPBL have been found to have a wide spectrum of cytologic appearances. At one end of the spectrum, smears are cellular with up to 30% single cells and large sheets in a complex configuration and exhibit nuclear enlargement and overlap and prominent nucleoli, features that overlap with those described in proliferative breast lesions.