Endocrine Abstracts

A rapidly growing neoplastic mass of the neck can either be caused by an anaplastic thyroid cancer (ATC) or a primitive lymphoma of the thyroid gland (PLT). These two malignancies share the same clinical features but vary widely in their treatment and outcome. Only histologic criteria through biopsy can provide a definitive diagnosis. The aim of this study was to assess biological and radiological differences between ATC and PLT in order to hasten differential diagnosis. Sixty-six patients were included, 33 ATC and 33 PLT, diagnosed between January 2000 and February 2016. Biological status (blood count, TSH, antithyroid peroxidase antibodies, CRP, β2 microglobulin and LDH) and imaging evaluation (Ultrasound (US) and computed tomography (CT) scanning) were compared. ATC patients were all from Lille University Hospital. PLT being less common, 16 patients were included from Lille and 17 from other hospitals in France. ATC was associated with higher leucocytes and neutrophils counts: over 10000/ml and 7500/ml with positive predictive values (PPV) of 77.3 and 75%, respectively. Neutrophils-to-lymphocytes ratio over 3,8 was noted in 77 and 48% of ATC and PLT patients, respectively. Thyroid tumor macrocalcifications and jugular vein thrombosis were found more frequently in ATC patients than in PLT patients with PPV for ATC of 93 and 77.8% respectively, regardless of the imaging technique (US or CT scan). PLT was associated with a thyroiditis history and/or high antithyroid peroxidase antibodies (PPV for PLT of 83 and 76.5% respectively). We conclude that blood count, antithyroid peroxidase antibodies measurement, search for tumor calcifications and jugular vein thrombosis provide basic and relevant information in the initial work-up of thyroid mass to distinguish between ATC from PLT.