Intraoperative imprint cytology for evaluation of mediastinal lymphadenopathy

Frozen-section (FS) analysis of mediastinal lymph nodes is commonly used in the staging of lung cancer and the evaluation of diagnostic tissue at mediastinoscopy. This approach facilitates definitive surgical intervention in a single operation and reduces costs. However, FS analysis can be labor intensive for the pathology department and time-consuming while the patient is anesthetized. Imprint cytology is more rapid than the FS procedure (average, 2 minutes versus 11 minutes per node) and allows more extensive sampling of the specimen. In this prospective study, we compared the diagnostic accuracy of imprint cytology and permanent sections on 121 mediastinal lymph nodes from 38 patients. There were no false-positive results and one false-negative result, although that patient was correctly classified based on positive cytology from another node. The sensitivity was 96.6%, the specificity was 100%, and the predictive value of a positive result was 100%, as no false-positives results were observed. The predictive value of a negative result was 98.9%, and the overall efficiency was 99.2%. These results compare favorably with those in other studies comparing the diagnostic accuracy of imprint cytology with that of FS analysis and with reported accuracy rates of FS technique. Our findings confirm the usefulness of this technique as an adjunct or substitute for FS analysis in the intraoperative pathologic evaluation of mediastinal lymphadenopathy.