Background: The objective of this study was to investigate the MSCT characteristics of PTL in order toenhance the awareness of this uncommon entity among both clinicians and radiologists. Materials and Methods:The clinicopathological data and MSCT images of 27 patients with PTL were retrospectively reviewed. TheMSCT appearances were classified into three types: type 1, solitary nodule surrounded by normal thyroid tissue;type 2, multiple nodules in the thyroid, and type 3, enlarged thyroid glands with a reduced attenuation with orwithout peripheral thin hyperattenuating thyroid tissue. Results: The patients were enrolled in the study witha mean age of 68 years (range, 51-86years) and compression symptoms or enlarged cervical lymph nodes atdiagnosis. Hashimoto’s thyroiditis was in 20 patients. All patients had non-Hodgkin lymphoma of B-cell in origin,including 22 cases of diffuse large B-cell lymphoma (DLBCL) and 5 of low-grade B-cell lymphoma of mucosaassociatedlymphoid tissue (MALT). For MSCT appearance, type 1 pattern was observed in 2 patients, type 2in 8, and seventeen type 3 in 17. The lesions occurred in more than one lobe with a mean maximal transversediameter of 6.9 cm and an ill-defined margin. Most tumors showed a homogeneous attenuation equal to that ofsurrounding muscles before contrast and obvious enhancement after contrast. Cervical lymph node involvementand invasion of the trahea and (or) esophagus were mainly observed in patients with DLBCL. Conclusions:PTL should be clinically considered in elder patients presenting with a history of Hashimoto’s thyroiditis andcervical lymphadenopathy. The MSCT characteristics of PTL includes a mass diffusely affecting more thanone thyroid lobe, isointense to muscle and obvious enhancement before and after contrast. DLBCL, the mostcommon histological subtype of PTL, is associated with a higher invasive tendency.
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