Thyroid Lymphoma

Objectives The purpose of this study was to correlate the clinicoradiologic and pathologic features of thyroid lymphoma and to identify the most useful diagnostic method for thyroid lymphoma as the first line. Methods Our study population included 16 patients with a diagnosis of thyroid lymphoma by fine‐needle aspiration, core biopsy, or surgery from 1995 to 2010. We retrospectively reviewed imaging and medical records. Sonographic findings were correlated with histopathologic results. Results Of the 16 patients, primary lymphomas were found in 13 and secondary in 3. The mean ages of the patients with primary and secondary lymphomas were 60.8 and 42.7 years, respectively. Most patients with primary lymphomas had symptoms of rapid neck swelling or a mass sensation. All primary lymphomas revealed non‐Hodgkin B‐cell lymphoma, and secondary lymphomas included a B‐cell origin in 2 and a T‐cell origin in 1. On sonography, 10 (77%) of 13 primary lymphomas showed diffuse heterogeneous hypoechoic parenchyma with intervening echogenic septa‐like structures, whereas all secondary lymphomas showed markedly hypoechoic nodules. Markedly hypoechoic parenchyma was correlated with lymphoepithelial lesions and neoplastic cells, whereas the intervening echogenic septa‐like structures were consistent with fibrosis on pathologic examination. The exact diagnosis of thyroid lymphoma was possible with core biopsy in all 9 cases (100%) but with fine‐needle aspiration in only 3 of 10 (30%), which included 7 under sonographic guidance and 3 under palpation ( P = .0030). Conclusions Diffuse hypoechoic parenchyma with intervening echogenic septa on sonography under the impression of a primary thyroid lymphoma, particularly in the setting of a rapidly enlarging mass, should prompt core biopsy rather than fine‐needle aspiration.