Large periampullary mass with vascular contact: Diagnostic and surgical decision-making in a solid pseudopapillary neoplasm.

Large periampullary masses with indeterminate origin and vascular contact represent a diagnostic and surgical challenge. While solid pseudopapillary neoplasm (SPN) is a rare pancreatic tumor with favorable prognosis, its presentation in the pancreatic head may lead to diagnostic uncertainty and influence operative strategy. A 37-year-old woman presented with a palpable right upper quadrant mass without systemic symptoms. Imaging revealed a large solid-cystic lesion in the cephalic-isthmic pancreas, closely abutting the superior mesenteric vein and exerting a mass effect on the duodenum. The exact origin of the tumor remained uncertain, raising the possibility of a duodenal gastrointestinal stromal tumor. Given this ambiguity, endoscopic ultrasound-guided biopsy was performed and confirmed SPN. The patient underwent pancreaticoduodenectomy. Intraoperatively, the tumor was found to be well encapsulated and separable from the mesenteric vessels, allowing complete resection without vascular reconstruction. The postoperative course was uneventful, and histopathology confirmed SPN with negative margins. This case highlights the limitations of imaging in periampullary masses and underscores the value of preoperative tissue diagnosis when the origin of the lesion is unclear. It also illustrates that vascular contact does not necessarily indicate invasion in SPN and should not preclude surgical resection. In the setting of a large periampullary mass with vascular contact, careful diagnostic assessment, including selective use of endoscopic ultrasound, can guide appropriate surgical management; recognition that vascular contact in SPN frequently reflects displacement rather than true invasion is essential to avoid misclassification and to ensure optimal, appropriately assertive surgical management.