Contrast-enhanced endoscopic ultrasonography differentiated pancreatic schwannoma from concurrent neuroendocrine tumor.

Pancreatic schwannomas are extremely rare and their variable imaging features on computed tomography (CT) and magnetic resonance imaging (MRI) make preoperative diagnosis challenging. A 73 year-old man was incidentally found to have a 13 mm hypoechoic mass in the pancreatic body on transabdominal ultrasonography. CT showed delayed enhancement, and MRI demonstrated hypointensity on T1, slight hyperintensity on T2, and hyperintensity on diffusion-weighted imaging (DWI). On endoscopic ultrasonography (EUS), the lesion appeared as a 13 mm hypoechoic mass, and contrast-enhanced EUS revealed gradual isoenhancement beginning 17 s after contrast injection. Another 6 mm hypoechoic lesion was identified in the pancreatic tail on EUS, and contrast-enhanced EUS showed rapid hyperenhancement beginning 12 s after contrast injection. EUS-guided fine-needle aspiration (EUS-FNA) was performed for both lesions, which were diagnosed as schwannoma and Grade 1 neuroendocrine tumor, respectively. A strategy of observation was adopted for both tumors. This is a rare case of concomitant pancreatic schwannoma and NET. EUS contributed to the detection of a small NET, while contrast-enhanced EUS revealed different vascular patterns between the two lesions, leading to a decision to perform EUS-FNA for both tumors.