Frozen Section in Diagnosis of Thyroid Swelling: Does It Still Have Role?

Purpose The present study correlates the frozen section diagnosis of thyroid swelling with the histopathological diagnosis and assesses the expression of immunohistochemical markers in malignant thyroid tumours. Also, the study aims to analyse the accuracy and limitations of the frozen section as an intraoperative tool for the diagnosis of thyroid swellings. Method Fifty-three cases of thyroid swelling were included in the study. Frozen section reports were classified as benign, malignant and deferred. A correlation between frozen section and histopathology examination (HPE) reports has been evaluated. The malignant cases confirmed on HPE were subjected to Immunohistochemistry (IHC) with TTF-1, Thyroglobulin, and CK-7. Results Among the 53 patients, 45 (84.9%) were females, and the majority were younger than 40 years (60.37%). On frozen section majority, 42 (79.25%) were benign, while a definitive diagnosis of malignancy was made in six cases (11.32%). On the frozen section, there were no false-positive cases, six true-positive cases, one false-negative case and 46 true-negative cases, with a sensitivity of 85.71%, specificity of 100%, the positive predictive value of 100%, the negative predictive value of 97.87% and diagnostic accuracy of 98.11% respectively. All the six papillary carcinomas and one follicular carcinoma showed immunoreactivity of tumor cells to TTF 1, CK 7 and Thyroglobulin. Conclusion There was a strong correlation between the frozen section and histopathological diagnosis. Still, it is not recommended in routine use for intraoperative diagnosis of thyroid swelling because of various limitations and the high diagnostic accuracy of FNAC. Adequate histopathologic diagnosis of thyroid disease is based on extensive subsampling of the specimen, which is not possible during an intraoperative frozen section procedure. If the frozen section is used, its limitations must be recognized, preferably based on first-hand data. © Association of Otolaryngologists of India 2021.