Number, size, and composition of cell clusters as related to breast FNA adequacy

The question of what types of parameters should be employed in establishing adequacy guidelines for fine-needle aspirations (FNAs) of palpable breast lesions remains without consensus opinion among cytopathologists. Although some investigators have suggested guidelines, based largely upon cellularit y standards, these have been somewhat conflicting, and the overall issue of whether or not cellularity is an appropriate measure of adequacy is contro versial. This study examines the number, size, and composition of cell clus ters in FNAs of palpable breast masses which had surgical follow-up, in all effort to identify characteristics of diagnostic aspirates which could con tribute to adequacy guidelines. Seventy-seven consecutive cases with surgic al follow-up were selected from four. quality-assurance (QA) categories (tr ue positive, TP; true suspicious, TS; tote negative, TN; and false negative , FN). All cases were evaluated in terms of overall cellularity (numbers of cell clusters), proportions of different-sized epithelial clusters (small, medium, and large), and proportions of epithelial to fibrofatty elements. Although the FN category showed the lowest average cellularity the applicat ion of cellularity cutoff values as a condition of adequacy would have resu lted in conspicuous numbers of cases from the "true" categories (TN, and to a lesser degree TS and TP) being rendered inadequate. For example, if case s with fewer than six epithelial clusters were excluded by virtue of inadeq uacy 69% of the FN cases would have been affected, along with 40% of the TN , 6% of the TS, and 4.5% of the TP. In terms of composition of the aspirate , neither proportions of the differently-sized epithelial clusters nor rati os of epithelial: fibrofatty elements reliably distinguished the "true" fro m the "false" diagnoses. This study concluded thar quantitative parameters alone are insufficient measures for determining specimen adequacy in FNA of palpable breast lesions. Rather adequacy remains based upon factors such a s confidence of needle placement, cell preservation, and correlation with c linical and mammographic findings. Diagn. Cytopathol. 1999;21:105-111. (C) 1999 Wiley-Liss, Inc.