Serous cystadenomas of the pancreas (SCP) are rare benign tumors, usually asymptomatic and diagnosed incidentally. Segmental portal hypertension (SPH) caused by vascular compression from an SCP is exceptional. We report a case in which endoscopy played a pivotal role in confirming SPH and guiding management.

An 85-year-old woman with a history of hypertension and type 2 diabetes presented with a gradually enlarging abdominal mass in the left flank and epigastrium. Laboratory tests were unremarkable. Abdominal CT revealed a 24 × 13 cm multiloculated mass originating from the pancreas, compressing the splenic vein, inferior mesenteric vein, and partially the portal vein, suggesting SPH.Upper GI endoscopy was performed to assess for portal hypertension and showed grade I esophageal varices and isolated gastric varices (IGV1), confirming SPH. Percutaneous biopsy of the mass demonstrated a multiloculated cystic lesion consistent with a benign serous cystadenoma without malignant features. The case was discussed in a multidisciplinary tumor board. Owing to the giant size of the lesion, vascular involvement, and the patient’s operative risk, surgical resection was not recommended. A conservative management strategy was adopted. Primary prophylaxis for gastroesophageal varices was initiated with non-selective beta-blockers. Clinical, endoscopic, and radiologic surveillance was planned.

This case highlights a rare complication of serous pancreatic cystadenomas: segmental portal hypertension secondary to major vascular compression. Endoscopy played a key role in diagnosing SPH, stratifying bleeding risk, and guiding therapeutic decisions. Awareness of this unusual presentation is essential to ensure appropriate multidisciplinary management of large benign pancreatic tumors.