Laparoscopic excision of a hypervascular mass confirms hyaline vascular-type unicentric Castleman disease in a patient with diabetesSurgery for a rare mass helps a woman with diabetes

Peripancreatic unicentric Castleman disease is rare and may mimic a primary pancreatic neoplasm because it often presents as a well-circumscribed hypervascular mass. We report a 26-year-old woman with type 2 diabetes mellitus in whom an incidentally detected upper abdominal mass was initially considered to arise from the pancreatic body. Computed tomography and magnetic resonance imaging showed a sharply marginated hypervascular lesion with diffusion restriction at the superior border of the pancreatic body, leading to a preoperative suspicion of pancreatic neuroendocrine tumor. Laparoscopic exploration revealed a well-encapsulated mass in the lesser sac closely abutting the superior surface of the pancreas. A clear dissection plane between the lesion and the pancreatic parenchyma allowed complete excision without pancreatic resection or splenectomy. Histopathological examination confirmed hyaline vascular-type unicentric Castleman disease. The postoperative course was uneventful, and no residual or recurrent lesion was detected during 1 year of follow-up; glycemic status also remained stable. This case highlights that close proximity of a hypervascular mass to the pancreas does not necessarily indicate pancreatic origin. Careful multiplanar imaging and direct intraoperative assessment of the lesion–pancreas interface may help determine the appropriate surgical extent and avoid unnecessary pancreatic resection when complete excision is technically feasible.