What makes Lymphadenopathy in Patients with Autoimmune Thyroiditis Suspicious for Malignancy?

AbstractLymphadenopathy in Robbins level II-IV and VI is common in autoimmune thyroiditis but the diagnostic strategy of a distinct lymphadenopathy exceeding the known features in autoimmune thyroiditis patients is unknown. The aim of this study was to determine how the extent of cervical lymphadenopathy in autoimmune thyroiditis affects the diagnostic management.The study comprises one index-patient with autoimmune thyroiditis and distinct suspicious lymphadenopathy in all cervical levels as well as retroclavicular. In addition 10 patients with autoimmune thyroiditis and distinct suspicious lymphadenopathy limited to level VI were evaluated.Findings of high resolution ultrasound, fine-needle aspiration cytology, serological testing and clonal analysis are reported here. Further diagnostics of the index-patient included histology, immunohistochemistry, bcl-2-expression analysis and PET/CT.The index-patient showed distinct lymphadenopathy in level I-VI and retroclavicular. Lymph nodes did not display any sonographic malignancy criteria. Molecular analysis and immunohistochemistry revealed monoclonal CD10- and CD20-positive, Bcl-2 expressing follicular B-cells confirming the diagnosis of a follicular B-cell Non-Hodgkin lymphoma.10 additional patients with limited lymphadenopathy showed typical features of autoimmune thyroiditis and lymph nodes did not display sonographic malignancy criteria in all cases. Further tests excluded lymph node malignancies.Extensive diagnostics in autoimmune thyroiditis and distinct cervical lymphadenopathy is crucial. Whereas limited lymphadenopathy in AIT was proven benign, extensive lymphadenopathy exceeding the known amount and/or spreading to retroclavicular/mediastinal compartments is suspicious for malignancy. Even in the absence of sonographic malignancy criteria further tests have to be performed.