Pancreatic schwannoma revealed contrast by contrast-enhanced ultrasonography: a case report.

An asymptomatic pancreatic tumor was discovered in a 77-year-old man during a medical check-up. An abdominal computed tomography (CT) and magnetic resonance imaging (MRI) revealed a cystic mass containing a septum-like solid portion in the head of the pancreas, measuring 3.5cm in diameter. Additionally, abdominal contrast-enhanced ultrasonography (US) revealed increased flow in the solid portion and a tumor capsule in its early phase. We preoperatively diagnosed the lesion as a cystic-degenerated pancreatic neuroendocrine tumor or solid-pseudopapillary tumor and performed a pancreatoduodenectomy. Histopathological examination revealed a cystic pancreatic mass consisting of spindle-shaped cells, with S-100-positive and SMA-negative immunohistochemical stainings. This lesion was diagnosed as a pancreatic schwannoma from these findings.