['Mesenterico-portal vein resection (PVR) during pancreatoduodenectomy for pancreatic head cancer was established in the 1990s and can be considered a routine procedure in specialized centers today. True histopathologic portal vein invasion is predictive of poor prognosis. The aim of this study was to examine the relationship between mesenterico-portal venous tumor infiltration (PVI) and features of aggressive tumor biology.', 'Patients receiving PVR for pancreatic ductal adenocarcinoma of the pancreatic head were identified from a prospectively maintained database. Immunohistochemical staining of tumor tissue was performed for the markers of epithelial-mesenchymal transition (EMT) E-Cadherin, Vimentin and beta-Catenin. Morphology of cancer-associated fibroblasts (CAFs) was assessed as inactive or activated. Statistical calculations were performed with MedCalc software.', 'In total, 41 patients could be included. Median overall survival was 25 months. PVI was found in 17 patients (41%) and was significantly associated with loss of membranous E-Cadherin in tumor buds (p = 0.020), increased Vimentin expression (p = 0.03), activated CAF morphology (p = 0.046) and margin positive resection (p = 0.005).'] Is histopathological tumor invasion of the mesenterico-portal vein characterized by aggressive biology and stromal fibroblast activation?