Low echogenicity of Hashimoto's disease could be useful in detecting early phase of thyroid lymphomas, especially diffuse large B cell lymphomas

Hashimoto's disease, characterized by low echogenicity on ultrasonography, is associated with thyroid lymphomas. Most thyroid lymphomas are diffuse large B cell lymphomas (DLBCLs) and mucosa-associated lymphoid tissue (MALT) lymphomas. DLBCLs have a worse prognosis than MALT lymphomas. This study aimed to evaluate the early signs, especially the low echogenicity, of Hashimoto's disease and thyroid lymphomas. This retrospective cohort study was conducted at Noguchi Thyroid Clinic and Hospital Foundation. A total of 9008 cases were operated on between 2008 and 2016, of which 162 had operated with suspected thyroid lymphoma, because of low echogenicity and aspiration biopsy cytology. The final diagnosis revealed 28 Hashimoto's disease, 134 thyroid lymphomas (91 MALT lymphomas and 43 DLBCLs). The primary outcomes were clinicopathological characteristics including low echogenicity of the thyroid. Early signs of thyroid lymphomas, especially DLBCLs were also investigated. Age, echo pattern, echogenicity anti-thyroid peroxidase antibody (TPOAb) and lactate dehydrogenase (LDH) were significantly different between Hashimoto's disease and thyroid lymphomas. Echogenicity, echo pattern and age were significant early signs of thyroid lymphomas. Age, echogenicity, soluble interleukin-2 receptor (IL2R), lactate dehydrogenase (LDH), and the neutrophil-to-lymphocyte ratio were significantly different between MALT lymphomas and DLBCLs. Echogenicity, and IL2R were significant early signs of DLBCL. The ROC analysis of low echogenicity for thyroid lymphomas compared to Hashimoto's disease revealed that Area Under the Curve (AUC) was 0.80 and the ROC analysis for DLBCL compared to Hashimoto's disease and MALT lymphoma revealed that the AUC was 0.73. Low echogenicity of Hashimoto's disease could be a useful early sign of thyroid lymphomas, especially DLBCL. The data that supports the findings of this study are available in the supplementary material of this article.