A focal nodular Hürthle cell hyperplasia in Hashimoto's thyroiditis: A diagnostic dilemma on fine needle aspiration

Hurthle cells are seen in a variety of nonneoplastic and neoplastic thyroid gland lesions. Number and morphology of Hόrthle cell vary in thyroid aspirate. Occasionally, thyroid aspirate in focal nodular Hόrthle cell hyperplasia in Hashimoto's thyroiditis exclusively comprise of Hόrthle cells and mimics Hόrthle cell neoplasm. Fine needle aspiration (FNA) diagnosis in such cases is challenging. A 60-year-old female presented with goiter and clinical features of hyperthyroidism. FNA smears showed Hόrthle cells arranged in flat sheets and lying singly with occasional lymphocytes in Hόrthle cell sheets. Repeat aspiration from other site showed lymphocytes, infiltrating the thyroid follicular cells. We conclude that a careful search of lymphocytes in Hόrthle cell sheets in cytology smears, multiple aspirates, associated clinical findings and ancillary techniques reduce the diagnostic pitfall and avoid unnecessary surgery.