Fine Needle Aspiration Cytology of Thyroid Lesions in a Tertiary Care Hospital Catering Predominantly the Tribal Population: Special Reference to Autoimmune Thyroiditis

Abstract

Introduction: The most common organ specific autoimmune disorder resulting in thyroid dysfunction is Autoimmune Thyroiditis (AITD). Fine Needle Aspiration Cytology (FNAC) is the most sensitive and most specific test for diagnosis of all clinically detectable thyroid lesions. But estimation of serum level of thyroid autoantibodies is necessary for the confirmation of AITD. In India, there are only few numbers of studies related to FNAC of thyroid lesions. There is also lack of convincing data regarding AITD in tribal populations in rural Bengal. Aim: To analyse FNAC of the thyroid lesions especially in respect to AITD among the tribal populations with biochemical and immunological parameters. Materials and Methods: The prospective observational study was done from January 2017-December 2018, in Department of Cytopathology and Biochemistry of BSMC, Bankura, India. Total 927 cases of thyroid lesions were diagnosed and classified. They were further associate biochemically and immunologically for the diagnosis of AITD. Data has been analysed in Microsoft Excel 2013 and with the help of Statistical Package for Social Sciences (SPSS) version 17. Agreement measure has been calculated using Cohen’s kappa coefficient statistical test. Results: Total 432 (46.6%) cases were diagnosed as colloid goitre, adenomatoid goitre was present in 132 (14.24%), malignancy was suspected in 84 (9%) patients, malignancy was present in 159 (17.15%) patients and lastly 120 (12.95%) cases were diagnosed as AITD cytologically. Among the cytologically diagnosed cases of AITD, number of female patients were 102 (85%), and maximum patients were hypothyroid. Among cytologically diagnosed cases of AITD, 113 (94%) patients were found biochemically positive for autoimmunity. The kappa values for FNAC vs anti-Thyroglobulin (TG) and FNAC vs anti-Thyroperoxidase (TPO), analysed, came to 0.74 for both, (p-value <0.0001) denoting substantial agreement (0.61-0.82). Conclusion: FNAC is a sensitive, specific, and accurate initial diagnostic test for evaluation of patients with thyroid swellings. AITD is the most common autoimmune disease affecting mainly the middle aged women. Antithyroid antibodies are good markers for the assessment of thyroid autoimmunity. Anti Thyroid Peroxidase (TPO) antibody is highly specific for AITD.