Cytomorphologic spectrum of lymphocytic thyroiditis and correlation between cytological grading and biochemical parameters

Introduction: Chronic lymphocytic thyroiditis [Hashimoto thyroiditis (HT)] is a common thyroid lesion diagnosed on fine-needle aspiration cytology (FNAC). Apart from FNAC, various other parameters, such as clinical features, ultrasonographic findings, antithyroid antibody levels, hormone profiles, and radionuclide thyroid scan, are also taken into consideration in making a diagnosis of HT. Aims: To grade lymphocytic thyroiditis based on the cytomorphology and to correlate the cytological grades with the levels of antithyroid peroxidase antibody (ATPO), antithyroglobulin antibody (ATG), and thyroid stimulating hormone (TSH). Materials and Methods: During a period of one and half years, 1,667 cases underwent FNAC of thyroid at our tertiary care center. Of these, 128 cases had cytological evidence of lymphocytic thyroiditis. Out of these, in 60 cases the levels of ATPO, ATG, and TSH were known. The cytological grades of lymphocytic thyroiditis in these cases were correlated with these parameters. Results: Out of the 60 cases, 55 were females. Age ranged from 5 years to 70 years, with majority of patients in third decade. Diffuse enlargement of thyroid was the commonest presentation. However, 14 cases presented with nodular disease. Majority of the patients had grade 1 thyroiditis (27 cases), followed by grade 2 thyroiditis (22 cases). Cytomorphology was diagnostic of thyroiditis in all 60 cases. ATPO was elevated in 57 cases and ATG was elevated in 40 cases. Elevated level of TSH was seen in only 18 cases. In 39 cases, TSH value was normal. There was no correlation between the cytological grades of thyroiditis and the levels of antithyroid antibodies and TSH. Conclusion: Lymphocytic infiltration of thyroid follicles is pathognomonic of lymphocytic thyroiditis. Positivity for antithyroid antibodies is strongly associated with HT but no correlation was observed between the grades of thyroiditis and the levels of ATPO, ATG, and TSH.