Morphological Study of Hashimoto Thyroiditis in Fine Needle Aspiration Cytology Specimens.

Background: Hashimoto thyroiditis is an autoimmune disease which is diagnosed based on well-defined clinical and cytological criteria. Purpose: The objective of this research is to study cytomorphological features in patients of Hashimoto thyroiditis and compare the findings with other studies. Literature on morphology of multinucleated giant cells was found to be lacking, and this study has focused on the number and morphology of these cells in this study. Material and Methods: FNAC was done in patients who met the clinical diagnostic criteria of Hashimoto thyroiditis formulated by "Japan Thyroid Association" and smears were analyzed by light microscopy. Data analysis was done by XLSTAT in Microsoft Excel 2010. The Wilcoxon Signed Rank Test was done to analyze the data on multinucleated giant cells. The null hypothesis was that the median of the population of differences between the paired data of small and large giant cells is zero. Results: A total of 26 patients were included in a period of one year. Contrary to observations in other studies, multinucleated giant cells were found in most participants. The Wilcoxon Signed Rank Test proved that small multinucleated giant cells were significantly more common than large multinucleated giant cells in Hashimoto thyroiditis; P value (two-tailed) being <0.0001 at significance alpha of 0.05. This study has also revealed that a few patients with Hashimoto thyroiditis can have large and very large multinucleated giant cells in a small number. Data on other cytomorphological features were no different than in other studies. Conclusion: The presence of multinucleated giant cells in 92.3% of patients in this study is far higher than in other studies which can have important diagnostic implications. Few large multinucleated giant cells can be present in a small number in a few patients as in Hashimoto thyroiditis.