BACKGROUND
The intraoperative frozen section is a well established procedure for rapid diagnosis that helps in making therapeutic decisions.
AIM
Assessment of the accuracy of frozen section diagnosis and analysis of the causes of its discordance.
METHODS
A retrospective review of 1695 surgical specimens performed in 1207 patients between January 2002 and April 2005. Frozen section results were compared with the final diagnoses in paraffin sections.
RESULTS
The frozen section diagnosis was benign in 84.2%, malignant in 10.2% and borderline in 0.4% of all cases. The frozen section result was deffered to permanent section in 5.2%. The sensitivity, specificity, positive and negative predictive values were 84.6%, 99.8%, 98.2% and 97.8% respectively. Overall diagnostic agreement was 97.5% (Kappa=0.88). Frozen section diagnosis was incorrect in 2.5% of cases. Most of the discrepancies were false negative cases frequently due to sampling errors and misinterpretation. False positive cases were always related with misinterpretation.
CONCLUSION
The frozen section evaluation is highly accurate and reliable. However, the surgeon and the pathologist must be aware of its limitations.