Lymphocytic Thyroiditis- Association between Cytology and Biochemical Findings

Introduction: Hashimoto’s thyroiditis otherwise called as chronic lymphocytic thyroiditis is the most common cause of hypothyroidism and one of the most common thyroid lesions in Fine Needle Aspiration Cytology (FNAC). Diagnosis depends on clinical findings, ultrasonographic findings, thyroid profile and antithyroid antibody levels along with the FNAC findings. Not much studies are there which have assessed the association of the clinical and biochemical parameters with the cytological findings. Aim: To grade the cytological features of lymphocytic thyroiditis and to study the association of the grades with Thyroid Function Test (TFT) and antithyroid antibody levels. Materials and Methods: A prospective time bound analytical observational study of one year was carried out in the Department of Pathology at Government Medical College, Palakkad, Kerala, India after obtaining approval from the Institutional Ethics Committee (IEC). Out of the total of 462 cases of thyroid lesions who underwent Fine Needle Aspiration (FNA), 147 cases were lymphocytic thyroiditis as per cytology. Of these, 40 cases had Thyroid Stimulating Hormone (TSH), Antithyroglobulin Antibody (ATG) and Antithyroid Peroxidase Antibody (ATPO) levels known which were included in the study. Cytological grading of those were done and the association of the same with the above mentioned parameters was studied. Data was analysed using Statistical Package for the Social Sciences (SPSS) software. Descriptive statistics were calculated and presented as percentages, mean and Standard Deviation (SD). Chi-square test was used to find the association between the categorical variables. The p-value <0.05 was taken as statistically significant. Results: Cytomorphology was diagnostic of thyroiditis in all the cases. Out of the 40 cases, 32 were females.The most common age group affected was 31-40 years, though it ranged from 18-68 years. Most common clinical presentation was diffusely enlarged thyroid, though a few presented as nodular disease. Most of the patients had grade 1 thyroiditis (23 cases) followed by grade 2 (13 cases). Elevated antithyroid antibody levels - ATPO elevated in 32 cases and ATG in 20 cases. TSH was seen elevated in 28 cases of thyroiditis. No association was observed with the antithyroid antibody levels and the cytological grade. Conclusion: Lymphocytic infiltration into the follicles is the diagnostic cytological feature of chronic lymphocytic thyroiditis. TSH elevation and positive ATPO levels strongly suggest Hashimoto’s thyroiditis. No association was found between the cytological grade and TSH and antibody levels.