Extra-pancreatic splenunculus masquerading as possible recurrent metastatic pancreatic neuroendocrine tumor after previous laparoscopic distal pancreatosplenectomy

Splenunculus is a benign mass characterized by the presence of ectopic splenic tissue outside the main spleen.Splenenculi occurring within the pancreas are often misdiagnosed as primary pancreatic neoplasms.Herein, we describe the case of a 64-year-old man with a subphrenic nodule detected on surveillance computed tomography performed 5 years after subtotal pancreatosplenectomy for pancreatic neuroendocrine tumor (PNET).A diagnosis of splenunculus was considered; however, the splenic scan did not reveal increased tracer uptake.Therefore, the nodule was surgically resected, followed by histopathologic examination, which confirmed the diagnosis of splenunculus.Extra-pancreatic splenunculus is uncommon, particularly in patients with prior primary PNET, presenting a diagnostic challenge.Additionally, a literature review was conducted to explore the potential challenges in diagnosis and management.