Tumor thrombus

Tumor thrombus is defined as tumor extending into a vessel, typically a vein. It occurs in a wide variety of malignancies. It is vital to distinguish tumor thrombus from "bland" thrombus (free of neoplastic cells) in the setting of neoplasia, as this often impacts staging and treatment approach.

Pathology

Tumor thrombus is usually composed of a soft tissue component and a thrombotic component.

Etiology

Tumor thrombus is perhaps most frequently associated with renal cell carcinoma, where tumor may invade the renal vein and grow caudally into the right atrium. However, this phenomenon is not isolated to renal cell carcinoma, and is recognized in :

Radiographic features

Ultrasound

Contrast-enhanced ultrasound is reported to be 100% sensitive and specific. The key feature of portal vein tumor thrombus is the presence of enhancement or color Doppler flow within the thrombus .

CT/MRI

Imaging features consistent with tumor thrombus on contrast-enhanced CT and MRI include:

  • presence of enhancement , the most specific sign
  • appearance of vessel expansion
  • diffusion restriction
Angiography

Streak and thread appearance of the tumor thrombus is characteristic in angiography due to parallel opacification of small vessels and arterial-venous shunting .

Nuclear medicine
FDG-PET

Increased activity associated with the presence of thrombus on CT

Treatment and Prognosis

In renal cell carcinoma, it may be possible to remove thrombus retrogradely at nephrectomy but the presence and nature of any tumor thrombus are important for determining the TNM stage.

In hepatocellular carcinoma (HCC), surgical resection is rarely performed in the setting of tumor thrombus given poor underlying liver function and high rate of recurrence even after liver transplant. For that, it is considered absolute contraindication to liver transplantation .

See also