Endocrine Abstracts

Introduction: The ability to diagnose thyroid cancers pre-op or intra operatively by Fine needle aspiration cytology (FNAC) or frozen section (FS) leads to the delivery of appropriate one stage surgical management. We aim to study the concordance and discordance of FNAC and FS with final histology in thyroid pathologies.

Methods: All thyroid procedures from 2007 to 2011 (n=423), involving FNAC and or Frozen Section (FS) in their management pathway were included. FNAC (n=159) were classified in a five tier system (non-diagnostic, benign, atypical, suspicious or malignant). FS (n=128) were classified as inconclusive, benign, suspicious or malignant. FNAC and FS were correlated with final histopathology.

Results: Out of 159 FNAC 72 (40.8%, PPV 92.8%) showed correlation with final histology. 61 (38.3%) were reported undetermined as Atypical (n=23), follicular neoplasm (n=27) or suspicious for malignancy (n=11). Within 61 undetermined FNAC there were 25 malignancies (40.6%) detected in final histology. Frozen sections; 104 out of 128 showed correlation (81.2%, PPV 99.0%). 15 false negative and one false positive FS were noted. Out of six suspicious FS; four showed benign pathology and two showed malignancies. There were two inconclusive FS showed malignancies in histology.

Conclusion: In conclusion, until now FNAC is considered as the best modality to triage the thyroid nodule pre operatively. Atypical and follicular neoplasm cytology categories warrants further clinical assessment and close follow ups when appear benign. The intra operative frozen sections are helpful to perform a one stage operation for suspicious thyroid lesion. This study also highlights the recognised limitation of intra operative frozen section analysis of thyroid neoplasia.