Primary thyroid lymphoma: CT findings Hyo-Cheol Kim a , Moon Hee Han a, *, Keon Ha Kim a , Hwan Jun Jae a , Sang Hyun Lee b , Sam Soo Kim b , Kwang Hyun Kim c , Kee-Hyun Chang a a Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Clinical Research Institute, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, South Korea b Department of Radiology, Kangwon National University College of Medicine, Ch’unch’on, South Korea c Department of Otolaryngology, Head and Neck Surgery, Seoul National University College of Medicine, Seoul, South Korea Received 19 February 2002; received in revised form 15 April 2002; accepted 17 April 2002 Abstract Introduction: To evaluate the computed tomographic (CT) findings of primary thyroid lymphoma. Methods and material: The clinicopathological data and CT images of nine patients with primary thyroid lymphoma were retrospectively reviewed. The CT appearances were classified into three types: type 1, a solitary nodule surrounded by normal thyroid tissue; type 2, multiple nodules in the thyroid, and type 3, a homogeneously enlarged both thyroid glands with a reduced attenuation with or without peripheral thin hyperattenuating thyroid tissue. Results: All patients had a rapidly enlarging thyroid mass and coexistent Hashimoto’s thyroiditis. One patient showed type 1 pattern, three type 2, and five type 3. Six patients had homogeneous tumor isoattenuating to surrounding muscles. The tumors had a strong tendency to compress normal remnant thyroid and the surrounding structure without invasion. Conclusion: Primary thyroid lymphoma should be included in the differential diagnosis when old female had a homogeneous thyroidal mass isoattenuating to muscles, which does not invade surrounding structures. # 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Thyroid, Neoplasms; Thyroid, CT; Lymphoma 1. Introduction Primary malignant lymphoma of the thyroid gland is uncommon, and accounts for 2.5  /5% of all thyroid malignancies [1,2]. The strong association of malignant lymphoma with Hashimoto’s thyroiditis has frequently been reported [1,2]. Most patients with the disease are elderly women who have a rapidly enlarging thyroid mass and symptoms of airway obstruction [1,2]. Ultrasound-guided fine-needle aspiration (FNA) is widely used to make the histopathological diagnosis of thyroid nodules [3]. A correct diagnosis with FNA was made in 60  /80% of patients with thyroid lymphoma [4,5]. Since patients with thyroid lymphoma are treated with radiation therapy and chemotherapy, limited surgery is usually required in these patients to obtain enough tissue for specific typing of the lymphoma [2,5]. Unnecessary surgical intervention may be, however, instituted due to the inaccuracy of preoperative FNA and a suspicion of carcinoma. Thyroid lymphomas are usually demonstrated with ultrasonography (US) as markedly hypoechoic areas, but this sonographic feature is nonspecific [6]. Dynamic enhanced MR images may suggest the diagnosis of malignant lymphoma nevertheless its high cost [7]. Contrast-enhanced CT has potential disadvantage lead- ing to blockage of nuclear medicine studies or Iodine- radiotherapy for months. If the CT appearances of this disorder are characteristic, however, one can suggest the possibility of thyroid lymphoma so that pathologists make more precise diagnosis by fine needle aspiration and unnecessary surgery can be avoided. In this study, we describe the radiological appearances of primary thyroid lymphoma by CT in nine patients. * Corresponding author. Tel.:  /82-2-760-2584; fax:  /82-2-743- 6385 E-mail address: hanmh@radcom.snu.ac.kr (M.H. Han). European Journal of Radiology 46 (2002) 233 /239 www.elsevier.com/locate/ejrad 0720-048X/02/$ - see front matter # 2002 Elsevier Science Ireland Ltd. All rights reserved. PII:S0720-048X(02)00134-1