The threads and streaks sign refers to an angiographic appearance of a vascularized tumor thrombus extending into the ipsilateral renal vein or the inferior vena cava from a renal cell carcinoma. This gives an appearance of linear, thread-like or string-like appearance of the involved vessel.
The same appearance also been described for tumor thrombus of the portal vein from hepatocellular carcinoma, where the vasa vasorum supplying the tumor thrombus can give rise to a transvasal intrahepatic arterioportal shunt 2.
Presence of this sign helps in surgical decision making 2.
It can be appreciated on angiography, CT, and MR imaging.