Fine needle aspiration cytology of Hashimoto's thyroiditis - A diagnostic pitfall with review of literature.

Hashimoto's thyroiditis is the second most common thyroid lesion next to goiter diagnosed on fine needle aspiration cytology (FNAC). It is also an important cause for hypothyroidism. FNAC plays a significant role in the diagnosis of thyroid lesions due to its simplicity and low cost. It can accurately diagnose Hashimoto's thyroidits in most patients. However, a small percentage of cases may be missed due to the inherent limitations of this procedure and the varied cytomorphology of this lesion. Therefore thorough cytological evaluation and an integrated approach are necessary to pick up correct diagnosis and to avoid unnecessary surgery. We present a 56-year-old female with solitary thyroid nodule diagnosed as Hurthle cell neoplasm on FNAC, but subsequent histopathological diagnosis following resection revealed Hashimoto's thyroiditis with marked Hurthle cell change.