Primary Thyroid Lymphoma: A Clinical Review

CONTEXT: Although primary thyroid lymphoma is a rare cause of both thyroid malignancy and extranodal lymphoma, awareness of this disease is important in order to achieve an early diagnosis and implement treatment. We review the epidemiology, clinical presentation, diagnosis, and treatment of this rare disorder. EVIDENCE ACQUISITION: This review is based on a search of PubMed and MDConsult for English language articles containing the term "primary thyroid lymphoma." The authors reviewed original and review articles and case series from all years of publication but focused on those published within the last 5 years. EVIDENCE SYNTHESIS: Primary thyroid lymphoma should be suspected in patients with a rapidly enlarging neck mass, especially in women with Hashimoto's thyroiditis. Certain ultrasound features such as enhanced posterior echoes can suggest the diagnosis, but biopsy for confirmation is ultimately needed. With advances in immunophenotypic analysis, fine-needle aspiration can be used for diagnosis in the hands of experienced physicians. The most common type of primary thyroid lymphoma is diffuse large B-cell lymphoma, which behaves in a more aggressive manner than mucosa-associated lymphoid tissue lymphoma. Radiation therapy can be employed for treatment of localized mucosa-associated lymphoid tissue lymphoma, but a combination of chemotherapy and radiation is needed for disseminated disease or aggressive histological subtypes. CONCLUSIONS: It is important to consider the diagnosis of primary thyroid lymphoma in patients presenting with an enlarging neck mass and a history of Hashimoto's thyroiditis. Advances in both diagnosis and treatment in recent years have altered our approach to the management of this disease.