Computed Tomography and Magnetic Resonance Imaging Findings of Malignant Solid Pseudopapillary Tumors of the Pancreas With Macroscopic Venous Tumor Thrombosis: A Report of 4 Cases

Multimodality Imaging of Abdominopelvic Tumors with Venous Invasion

A broad range of abdominal and pelvic tumors can manifest with or develop intraluminal venous invasion. Imaging features at cross-sectional modalities and contrast-enhanced US that allow differentiation of tumor extension within veins from bland thrombus include the expansile nature of tumor thrombus and attenuation and enhancement similar to those of the primary tumor. Venous invasion is a distinctive feature of hepatocellular carcinoma and renal cell carcinoma with known prognostic and treatment implications; however, this finding remains an underrecognized characteristic of multiple other malignancies-including cholangiocarcinoma, adrenocortical carcinoma, pancreatic neuroendocrine tumor, and primary venous leiomyosarcoma-and can be a feature of benign tumors such as renal angiomyolipoma and uterine leiomyomatosis. Recognition of tumor venous invasion at imaging has clinical significance and management implications for a range of abdominal and pelvic tumors. For example, portal vein invasion is a strong negative prognostic indicator in patients with hepatocellular carcinoma. In patients with rectal cancer, diagnosis of extramural venous invasion helps predict local and distant recurrence and is associated with worse survival. The authors present venous invasion by vascular distribution and organ of primary tumor origin with review of typical imaging features. Common pitfalls and mimics of neoplastic thrombus, including artifacts and anatomic variants, are described to help differentiate these findings from tumor in vein. By accurately diagnosing tumor venous invasion, especially in tumors where its presence may not be a typical feature, radiologists can help referring clinicians develop the best treatment strategies for their patients. ^©RSNA, 2020.

Tumor thrombosis: a peculiar finding associated with pancreatic neuroendocrine neoplasms. A pictorial essay

While abutment, encasement or vessel occlusion are identified in most patients with a pancreatic tumor, tumor thrombosis is an uncommon finding. In particular, there are no description in the literature of tumor thrombosis associated with ductal adenocarcinoma, the most common pancreatic tumor. On the other hand, surgical series reveal that tumor thrombosis is associated with about 5% of pancreatic neuroendocrine neoplasms (PanNENs), and literature data suggest that this finding is frequently underreported on pre-operative imaging examinations. Tumor thrombosis may be clinically relevant, causing splenoportomesenteric hypertension, possibly responsible for life-threatening upper gastrointestinal bleeding. Bland thrombosis caused by direct infiltration of peri-pancreatic vessels frequently determines surgical unresectability, even in neuroendocrine tumors; on the opposite, tumor thrombosis associated with PanNENs do not exclude surgery per se, even though both morbidity and mortality can be increased by such condition. Considering the favorable prognosis of PanNENs and the frequent need to treat tumor thrombosis in order to prevent complications or to relieve symptoms, it is of paramount importance for radiologists the knowledge of the variety of findings associated with tumor thrombosis in PanNENs.