Benign on cytology, malignant on histopathology: Coexistence of Hashimoto’s thyroiditis with Papillary carcinoma of thyroid

Papillary thyroid carcinoma (PTC) and Hashimoto’s thyroiditis (HT) are common diseases in clinical practice. Hashimoto’s thyroiditis is the most common autoimmune thyroid disease and the most common cause of hypothyroidism. It is characterized by diffuse lymphocyte infiltration, fibrosis, and parenchymal atrophy. Papillary thyroid carcinoma is the most common malignant neoplasm of the thyroid. There is a high prevalence of association between HT and PTC. FNAB is useful for diagnosing PTC in patients with HT associated thyroid lesions. The presence of HT in patients with PTC was associated with disease presentation at an earlier stage, less aggressive clinical course and better outcome. Here we have presented a case of hashimoto's thyroiditis with papillary thyroid carcinoma in a 37 years old female who came with complaints of swelling in front of neck. Cytology and radiology showed features of HT but, on histopathology it was diagnosed as HT with PTC.