Autoimmune thyroiditis - Correlation of cytomorphological features and AMA titre

Background: Thyroiditis is the second most common thyroid lesion next to endemic goitre diagnosed on FNA in iodine (I2) deficient areas. Aim: This study was carried out to study correlation between various cytomorphological features with anti-thyroid antibodies in cases of autoimmune thyroiditis diagnosed on FNAC. Materials and methods: This was a retrospective study carried out in a tertiary care teaching hospital. 150 cases diagnosed as autoimmune thyroiditis in a two year period from January 2010 to December 2011 formed the study group. The cytological findings and AMA tires were noted from the medical record available with the patient and also from Endocrinology department records. Results: Incidence of autoimmune thyroiditis was found to be 13.4%. Majority of the patients were females (96.7%), 53.3% of cases were seen in 21-40 years age group. In 97 patients anti-microsomal antibody titre (AMA) was available, 83 were positive i.e.85.6% positivity. Association between grade of lymphocytes, grade of thyroiditis and high L:E ratio with AMA titre was found to be statistically significant. Of the cytologically diagnosed cases of autoimmune thyroiditis, 14.4% cases showed AMA negativity. Thus FNAC remains the gold standard for the diagnosis. Conclusion: Grade of lymphocyte infiltration and grade of thyroiditis correlated well with AMA positivity. Association between high L:E ratio and AMA titre was found to be statistically significant.