Cytomorphologic study of Hashimoto's thyroiditis and its serologic correlation: a study of 150 cases

To analyze the cytomorphologic spectrum of Hashimoto's thyroiditis (HT) on fine needle aspiration cytology (FNAC) and to correlate cytologic findings with serologic parameters

One hundred fifty patients diagnosed with HT on FNAC were subjected to serologic studies. A detailed cytologic examination was done with an attempt to grade thyroiditis, lymphoid:epithelial (L:E) ratio and intensity of lymphocytic infiltrates. Any additional lesion or feature seen in association with HT was recorded. Thyroid hormonal assay and thyroid antibodies were evaluated using appropriate methods. Cytologic findings were correlated with the serologic parameters and analyzed using the chi2 test and Fisher's exact test.

Apart from the usual cytomorphologic spectrum of HT, significant findings recorded in a fair number of cases were abundant colloid, follicular hyperplasia, fire flares, eosinophils and HT-associated neoplasms. Grading of thyroiditis and lymphocytic infiltration showed no correlation with the clinical severity of HT, while a high L:E ratio was strongly correlated with thyroid peroxidase positivity (p = 0.004). Presence of fire flares and macrophages correlated positively with hyperthyroidism, with p values of 0.002 and 0.005, respectively. Thyroid peroxidase positivity showed a strong association with HT (p = 0.001) as compared to HT coexisting with follicular hyperplasia/Hashitoxicosis/neoplasm.

The present study gives an account of the cytomorphologic spectrum of a large series of HT cases, with its serologic correlation, emphasizing the importance of a careful interpretation of fine needle aspiration smears in the presence of colloid, follicular hyperplasia or a coexisting neoplasm.