Follicular lymphoma of the thyroid and the role of core needle biopsy

Abstract

Summary Primary thyroid lymphoma (PTL) is a rare malignancy, accounting for less than 5% of all thyroid neoplasms. The follicular subtype is even more rare, accounting for approximately 10% of all PTL cases. We report a case of a 64-year-old woman, who presented with a rapidly growing goitre with mass effect and B symptoms. She had a history of Hashimoto’s thyroiditis and her thyroid ultrasound revealed diffuse goitre with a dominant nodule (56 × 63 × 60 mm) within the right thyroid lobe. Ultrasound-guided percutaneous fine-needle aspiration of the right thyroid nodule was classified as benign, according to Bethesda System, with lymphocytic thyroiditis. A CT scan of the neck showed diffuse enlargement of the thyroid gland extending towards the anterior mediastinum with tracheal deviation and lymphadenopathy within levels VII and right II–IV. The core needle biopsy of the right thyroid nodule revealed a follicular non-Hodgkin’s B cell lymphoma with a Ki67 of 60%. According to the Ann Arbor staging system, she was at stage IIIE. She underwent chemotherapy with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) with remarkable clinical improvement and is currently in remission 2 years after the diagnosis. PTL is an extremely rare malignancy that usually arises in a lymphocytic thyroiditis background, presenting as a rapidly enlarging goitre, which can lead to compressive symptoms or airway comprise. Learning points Primary thyroid lymphoma (PTL) is a rare malignancy, accounting for less than 5% of thyroid neoplasms. PTL should be suspected when a patient presents with a rapidly enlarging goitre, especially in the setting of Hashimoto’s thyroiditis. Fine-needle aspiration has a limited capacity for PTL diagnosis due to similar cytomorphological features of lymphoma with thyroiditis. Therefore, in case of clinical suspicion and if fine needle aspiration fails to diagnose PTL, a tissue biopsy should be performed. Treatment is dependent on both the stage and histology of PTL. Chemotherapy and local radiotherapy remain the mainstay treatment for PTL.