Cytological Grading of Chronic Thyroiditis

Seventy six consecutive patients attending our FNAC clinic from January 2002 to December 2004 and clinically presumed to have chronic lymphocytic/autoimmune thyroiditis were recruited for this study. A written consent was obtained from each patient for inclusion in the study. The patients had estimation of T3, T4, TSH, thyroid microsomal antibodies (using serodia AMC Kit), ¹³¹I-thyroid uptake and high resolution thyroid USG (using 7–12 MHz Broad band linear transducer on HDI 5000 of ATL, Japan) to locate macronodules (focal lesions ≥ 5 mm in diameter).
Fine needle aspiration of the thyroid was performed from several locations. USG guidance was not used for the procedure. Smears were prepared and stained with May Grunwald Giemsa, Papanicolaou/Haematoxylin and eosin. In case the material obtained was not satisfactory a repeat aspiration was done but not more than 2–4 aspirations were tried on each patient. The smears were seen by two independent cytologists. Qualitative criteria used for cytologic diagnosis were lymphocytes and plasma cells infiltrating the thyroid follicles and increased number of lymphocytes in the background with or without lymphoid follicles, Hurthle cell change, multinucleated giant cells, epithelioid cell clusters, anisonucleosis or interlobular fibrosis that is the presence of fibrous tissue or scattered fibroblasts in the aspirate. Quantitation of thyroiditis was done by a cytological grading system based on number of lymphocytes infiltrating the gland, the degree of destruction caused (relative proportion of inflammatory and follicular epithelial cells) and presence of associated features like Hurthle cell change, giant cells, anisonucleosis etc (Table 1). Mann Whitney and chi-square tests were used for statistical correlation and p-value of <0.05 was considered significant.