Rapid cell blocks improve accuracy of breast FNAs beyond that provided by conventional cell blocks regardless of immediate adequacy evaluation.

A new "rapid cell block" technique (RCB; the predecessor of Cellienttrade mark Automated Cell Block System) is efficient at recovering sparse material. We previously found that RCBs of breast fine-needle aspirations (FNAs) frequently allow histologic classification of problematic ductal proliferative lesions. Previous studies that did not emphasize cell blocks found that on-site evaluation (OSE) of breast FNAs improves diagnosis. The purpose of this study was to determine if RCB could replace the utility of OSE of breast FNAs. The study included 604 consecutive ultrasound-guided noncyst breast FNAs composed of three cohorts based on the presence or absence of immediate adequacy assessment, conventional (collodion bag) cell blocks (CCB), and RCB. The cohort with OSE together with CCB did not perform as well as the cohort without OSE but with RCB. In a third cohort, performance characteristics of RCBs and CCBs were compared in an independent review by two cytopathologists blinded to the final cytology and follow-up histology diagnosis. By itself, the RCB histologic section was diagnostic 97% of the time, and it provided a diagnostic accuracy superior to CCB by itself and comparable to that provided by the combination of the smears with CCB. Highest accuracy was obtained by combining smears/monolayer preparations and RCB. Replacing OSE with RCBs provided substantial cost savings and savings of time for cytopathologists, radiologists, and their assistants.