Threads and streaks sign | Radiology Signs

The threads and streaks sign occurs due to a vascularized tumor thrombus extending into a vein, commonly the renal vein or portal vein, from an aggressive malignancy such as renal cell carcinoma or hepatocellular carcinoma. This tumor thrombus is infiltrated and supplied by tumor neovascularity or arterial collaterals, creating multiple fine linear vascular channels within the involved vessel lumen on angiography, CT, or MRI.

Why is it called so?

It is named “threads and streaks” because angiographically or on cross-sectional vascular imaging it appears as multiple thin, thread-like linear vascular structures or streaks within the vessel lumen that contrast with the normal blood flow, resembling strings or threads coursing along the vessel.

Pathophysiology

The sign arises from tumor growth into the vessel lumen forming a tumor thrombus supplied by neovascularization and arterioportal or transvascular shunts. These vessels, often representing vasa vasorum or arterial collaterals, create linear enhancing channels inside or around the thrombus during the arterial phase of imaging, resulting in the characteristic thread-like vascular pattern. This reflects active tumor angiogenesis and direct intravascular tumor extension, distinguishing tumor thrombus from bland thrombus.

Alternative names: Striated vascular sign (in hepatocellular carcinoma)

Other associated named signs: None specifically linked, but it is related to tumor thrombus imaging features used in surgical planning and staging.