Thyroid lymphoma is a rare malignant tumor constituting 1% to 2% of all thyroid malignancies and less than 2% of lymphomas. Thyroid lymphomas are classified as non–Hodgkin's B-cell lymphomas in a majority of cases, although Hodgkin's lymphoma of the thyroid has also been identified. Thyroid lymphoma is a rare malignant tumor constituting 1% to 2% of all thyroid malignancies and less than 2% of lymphomas. Thyroid lymphomas are classified as non–Hodgkin's B-cell lymphomas in a majority of cases, although Hodgkin's lymphoma of the thyroid has also been identified. As with other thyroid lesions, thyroid lymphoma affects predominantly females over 70 years of age with a history of Hashimoto's thyroiditis. Thus, Hashimoto's thyroiditis is considered a risk factor for thyroid lymphoma development.Thyroid lymphoma manifests as a rapidly enlarging neck mass which may compress the nearby trachea causing respiratory difficulty. On physical examination, patients usually exhibit a firm thyroid and lymphadenopathy. Thyroid lymphoma poses a diagnostic and therapeutic challenge. This is because several manifestation patterns are similar to those of anaplastic thyroid cancer (ATC). Fine-needle aspiration (FNA) helps distinguish the two entities preoperatively. The majority of thyroid lymphomas are non–Hodgkin's B-cell lymphomas; a minority exhibit properties of T-cell lymphomas .