Papillary carcinoma of thyroid presenting as posterior mediastinal mass with superior vena cava syndrome.

Enlarged thyroid with retrosternal extension presenting as anterior mediastinal mass is known. Superior vena cava (SVC) syndrome due to direct invasion from a primary thyroid malignancy is a rare phenomenon. We present a unique case of papillary carcinoma of thyroid extending into the posterior mediastinum with superior vena cava syndrome along with internal jugular and azygous vein thrombosis.