A 65-year-old patient presented with extensive swelling of the lateral neck. B-mode ultrasound showed an oval, well defined, hypoechoic formation consisting of multiple circular layers extending from the base of the skull to the subclavian vein. On subsequent computed tomography the size of the lesion was confirmed and the cause, a mediastinal mass compressing the superior caval vein, was identified. Histological examination of the mass revealed a neuroendocrine active non-small-cell-cancer of the lung. Treatment with high-dose heparin and antibiotics was started immediately, combined with palliative chemotherapy.The differential diagnosis of neck masses includes congenital, infectious, neoplastic and secondary causes due to disease in other regions of the body. Etiologies for jugular vein thrombosis include prolonged central venous catheterization, trauma, obstruction, infection as well as hypercoagulation. In order to diagnose masses in the head and neck region, other parts of the body need to be successively included if no local cause can be identified.