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

Abstract

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.

Macrovascular venous invasion of pancreatic neuroendocrine tumours: impact on surgical outcomes and survival

“…Pancreatic neuroendocrine tumours (PNETs) are characterized by greater tropism for direct vascular spreading. 1 This pattern of tumoral spread, also known as macrovascular venous invasion (MVI), might manifest with venous tumoral thrombus (VT) and/or direct venous wall invasion (VWI). 2 The exact incidence of MVI in PNETs remains not clearly defined, with less than 5% of cases reported in historical series.…”

“…1,6 -8 Surgical resection of PNETs with MVI is perceived as challenging to be performed, because of an increased risk of intraoperative haemorrhage in presence of PH. 1,2 Because of the paucity of data reported in the literature, the results of surgical resection of PNETs with MVI as well as the prognostic impact of venous invasion in these patients remain scarcely evaluated. 2,[9][10][11][12][13][14][15] This study aimed to evaluate the incidence, the impact on surgical outcomes and the survival of patients having PNETs with MVI resected at our centre.…”

Mesenteric Variceal Haemorrhage and Ectopic Cushing’s Syndrome as Presenting Features of a Pancreatic Neuroendocrine Tumour Recurrence

“…Pancreatic malignancies are known to commonly abut or encase local vasculature and can cause obstruction either via external compression or bland thrombosis [ 10 ]. pNETs conversely are unique in their ability to cause tumour thrombosis and venous wall invasion, features not seen with pancreatic adenocarcinomas [ 10 ]. Historically, this was thought to be a rare occurrence [ 11 ]; however, a more recent study found evidence of local venous tumour thrombosis in 33% of CT scans of non-functional pNETs, with 62% of the initial scan reports omitting this finding [ 12 ].…”

Imaging presentation of pancreatic neuroendocrine neoplasms

“…In case of vessels involvement, this particular growing pattern is usually confined to peri-pancreatic vessels, such as splenic and portal veins, producing a neoplastic thrombus, characterized by enhancement during contrast media imaging studies, quite the opposite of blood clot thrombus [ 33 ].…”