A Resected Case of Leiomyosarcoma Originating from the Splenic Vein with a Preoperative Diagnosis of Pancreatic Tumor

A 77-year-old female presented to a doctor at a nearby medical clinic complaining of heartburn. She was diagnosed with a pancreatic mass on ultrasound (US) and was referred to our hospital for further examination. Contrast abdominal CT revealed a 22 mm tumor that markedly compressed the splenic vein on the pancreatic body. We determined that the pancreatic tumor had invaded the splenic vein and planned subtotal stomach-preserving pancreaticoduodenectomy (SSPPD) with combined resection of the portal vein. During surgery, the tumor was found to be inside the splenic vein without invasion to the pancreatic parenchyma. The tumor appeared to originate from the vessel wall. By the time we recognized this, we had almost completed resection of the pancreatic head. We then performed SSPPD with reconstruction of the portal and splenic veins. The pathological diagnosis was leiomyosarcoma originating from the splenic vein. Preoperative diagnosis of leiomyosarcoma originating from the splenic vein is difficult. In almost all reported cases, pancreatectomy was performed under the diagnosis of pancreatic tumor. To avoid unnecessary pancreatectomy, when we encounter a pancreatic tumor that has invaded the portal vein system, we should consider this rare disease during the differential diagnosis process.