Endocrine Abstracts

Internal jugular vein thrombosis (IJVT) is generally related to central venous access devices (CVADs) because of endothelial trauma or inflammation. Other reported causes include neck surgery complication, malignancies, deep neck infections, intravenous drug abuse, ovarian hyperstimulation syndrome and hypercoagulable states.

We report the case of a 47-year-old woman presenting with acute neck pain, local swelling and fever. Neck ultrasound with Doppler studies showed a goiter of 48 ml with a heterogeneous parenchyma and a left internal jugular vein thrombosis of recent appearance. Blood tests revealed elevated inflammatory markers, overt hyperthyroidism (TSH <0.04 μUI/ml, FT₄ 3 ng/dl, FT₃ 7.9 pg/ml) and high serum thyroglobulin (183 ng/ml). Anti-thyroid autoantibodies were absent. Technetium-99m pertechnetate scintigraphy showed a very low uptake, suggestive of thyroiditis. Nonsteroidal anti-inflammatory treatment was administered, in addition to low-molecular weight heparin. The most common causes of IJVT were investigated. A complete screening of inherited and acquired pro-thrombotic factors was negative. ¹⁸F-FDG PET/CT showed an unusually intense and diffuse uptake in thyroid gland, with extension to surrounding tissues and multiple bilateral adenopathies, strongly evocative of a thyroid lymphoma. A progressive decrease of neck pain and swelling was observed, and a wait and see attitude was decided. After 6-month delay, the complete normalisation of ¹⁸F-FDG PET/CT and neck ultrasound was observed, confirming the diagnosis of subacute thyroiditis. Very limited data are reported in literature on the correlation between deep venous thrombosis and subacute thyroiditis. Some reports on sinus or cerebral thrombosis after thyrotoxicosis suggests that hyperthyroidism could be associated with a hypercoagulable state. The exact mechanism is still unknown. This case shows that in a patient with subacute thyroiditis presenting with persistent neck pain and swelling, IJVT must be ruled out. We discuss the diagnostic challenge represented by intense and diffuse hypermetabolic activity in thyroid gland at ¹⁸F-FDG PET/CT.