Feasibility of imprint cytology for evaluation of mediastinal lymph nodes in lung cancer

Background: Intraoperative evaluation of mediastinal lymph nodes is a necessary step which helps us to decide whether or not to continue the operation of lung cancer. Imprint cytology (IC) can be used as an alternative method in staging. It is a more rapid and simpler procedure than frozen section (FS) analysis. Therefore, we compared the diagnostic accuracy of IC with permanent section on 1050 mediastinal lymph nodes. Methods: A total of 255 non-small cell lung cancer patients who underwent surgical procedure between January 1995 and April 2004 were included. There were 236 males and 19 females with a mean age of 54.2 years (range 26-79 years). In order to obtain lymph node samples mediastinoscopy was performed in 232 (91%), anterior mediastinotomy in 50 (20%) and video-assisted thoracoscopic surgery in 16 (6.3%) patients. During final pathological diagnosis, both imprint and permanent section slides were compared. Results: There were five false-positive and eight false-negative results. The sensitivity, specificity and the predictive values for positive and negative results were 93.1, 99.5, 95.6 and 99.1%, respectively. The overall efficiency was 98.8%. Conclusions: The diagnostic IC is an accurate, reliable, simple and less time-consuming method for evaluation of mediastinal lymph nodes in lung cancer, compared with FS method.