Application of pattern analysis in fine needle aspiration of solitary nodule of thyroid

BACKGROUND: Various methods are used to arrive at a conclusive diagnosis of thyroid lesions on fine needle aspiration cytology (FNAC). Systemic pattern analysis is one such that can be used to analyze the lesions and divide them into individual categories. AIMS: To study the application of pattern analysis in the interpretation of solitary thyroid nodule (STN). MATERIALS AND METHODS: Two hundred and nineteen cases of fine needle aspiration cytology of STN were reviewed along with histopathological correlation. Smears were classified based on primary and secondary patterns. Predominant pattern (primary) was identified and lesion categorized. This was followed by identifying the next dominant pattern (secondary) and recategorization. Cytological diagnosis based on primary and secondary patterns was correlated with the histopathological diagnosis. RESULTS: Based on pattern analysis, the study had a sensitivity of 66.7% and specificity of 98.9%. The positive predictive value and negative predictive value were 88.9% and 96% respectively and the overall diagnostic accuracy was 95.4%. CONCLUSIONS: The present study demonstrates the feasibility and applicability of pattern analysis in diagnosing thyroid lesions by FNAC, which could be easily reproducible.