Cytomorphological Aspects of Hashimoto's Thyroiditis: Our Experience at a Tertiary Center.

Introduction: Hashimoto's thyroiditis is the most common form of acquired hypothyroidism. Fine needle aspiration cytology is one important tool in diagnosing Hashimoto's thyroditis, along with clinical, biochemical, immunological and ultrasonographical modalities. The present study examines cytological aspects of Hashimoto's thyroiditis along with their correlation with clinical, biochemical and immunological findings, whenever available.

Materials and methods: This is a retrospective study of 50 cases of Hashimoto's thyroiditis. Cytological findings were reviewed and correlated with clinical, biochemical and immunological findings whenever available.

Results: The majority of the patients were middle-aged females, with a female to male ratio of 6.14:1. Most patients presented with diffuse thyromegaly (68%) and/or hypothyroidism (56.09%). The antibody profile was available in 22% of patients. Of these, anti-thyroid peroxidase antibodies were raised in 81.81% of patients and anti-thyroglobulin antibodies were raised in 63.63% of patients. In the present study, high lymphoid to epithelial cell ratio was seen in 78% of cases, and 74% of cases showed Hurthle cell change. Follicular atypia was seen in 36% of cases. Lymphoid follicle formation was seen in seen in 54% of cases. Follicular cell infiltration by lymphocytes, eosinophils and neutrophils was seen in 72%, 48% and 26% of cases, respectively. Plasma cells were seen in 18% of cases.

Conclusion: Thyroid function tests and immunological tests cannot diagnose all cases of Hashimoto's thyroiditis. Fine needle aspiration cytology continues to be a diagnostic tool of significance in diagnosing Hashimoto's thyroiditis. The presence of inflammatory cells, particularly lymphocytes and eosinophils, was detected in a significant proportion of cases.