Primary thyroid lymphoma: A rare disease.

Primary thyroid lymphomas are rare neoplasms comprising of 1-5% of thyroid malignancies. These are predominantly B-cell in origin. Here, we report a case of 60 years lady, a known case of lymphocytic thyroiditis, diagnosed as thyroid lymphoma (diffuse large B-cell) on fine needle aspiration and confirmed histopathogically and immunohistochemically. She presented with a sudden increase in thyroid swelling. Fine needle aspiration performed showed highly cellular smears comprising predominantly of the monomorphic population of medium to large sized lymphoid cells with high nuclear/cytoplasmic ratio and scant cytoplasm. A possibility of thyroid lymphoma possibly diffuse large B-cell lymphoma was suggested which was later confirmed on biopsy. Fine needle aspiration provides an easy mode for diagnosing large cell lymphoma like diffuse large B-cell. Hence, an early diagnosis is possible for a timely intervention. Also, cases of lymphocytic thyroiditis should be regularly followed for the development of lymphoma.