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.

Purpose: The purpose of this study was to report the imaging findings of malignant pancreatic solid pseudopapillary tumors (SPTs) with macroscopic venous tumor thrombi.

Methods: The clinical features and imaging findings of 4 cases of malignant pancreatic SPT with venous tumor thrombi were retrospectively reviewed.

Results: The tumor thrombi were located in the splenic vein (n = 3) or the main portal vein and the proximal splenic vein (n = 1). Venous thrombi were connected with the main pancreatic tumors and showed venous filling defects on computed tomography and magnetic resonance imaging. Tumor thrombi primarily consisting of necrotic component and/or hemorrhage displayed no enhancement after contrast injection (n = 3). The enhancement pattern of the tumor thrombi that consisted mainly of tumor nests was consistent with pancreatic SPT (n = 1), that is, a slight enhancement in the arterial phase and a progressive enhancement in the portal venous phase and the equilibrium phase. Venous tumor thrombi associated with hemorrhage were hyperintense on both T1-weighted and T2-weighted images.

Conclusions: It is uncommon for pancreatic SPTs to spread by invading the venous system and forming macroscopic venous tumor thrombi.