Cell Pattern Analysis in Fine Needle Cytology of Solitary Thyroid Nodule with Histopathological Correlation

Introduction:Adequacy of thyroid aspirate comprise five to six groups of thyroid follicular epithelial cells with each group containing 10 or more cells on atleast two smeared slides. Thyroid fine needle cytology (FNC) can be used for cell pattern analysis.Aims:To study pattern analysis of solitary thyroid nodules (STN) and to assess diagnostic parameters for cytodiagnosis of thyroid lesions.Materials and Methods:Forty-seven cases of STN were subjected to cell pattern analysis and correlated with histopathological diagnosis. Aspirate smears were classified based on primary pattern and secondary pattern. Primary pattern was the most dominant pattern seen. The next co-dominant pattern was labelled as secondary pattern. The final Bathesda based cytological diagnosis was categorised based on these two patterns in each case. Histopathology report of these cases after surgery was correlated with the cytological diagnosis. For each correlation; sensitivity, specificity, positive predictive value, diagnostic accuracy was calculated by appropriate formula manually. Kappa measure of agreement was used for inter-observer variation. Results:Based on the cell pattern analysis of STN cases, the diagnostic parameters in our study were: Sensitivity-71.43%, Specificity-97.5%, Positive predictive value-83.33%, Accuracy or Efficacy-93.62%, False positive rate-2.43%, False negative rate-4.26%. Conclusion:The present study demonstrates the application of pattern analysis in diagnosing thyroid lesions on FNC which are easily reproducible. Also, such study can help beginners in pathology field to understand systematic arrival at a cytological diagnosis that helps triage neoplastic from non-neoplastic thyroid lesions.