The imaging features favor a pancreatic serous cystadenoma. A side branch IPMN is felt less likely given it is an isolated lesion with no communication with the pancreatic duct is seen. 

The patient was then submitted to an EUS with FNA. The appearances on the ultrasound (not available) were typical for a serous cystadenoma. FNA: 

• CEA: <5 ng/ml
• Ca19.9: 0.5 U/mL

Note that carcinoembryonic antigen (CEA) values are low in serous cystadenomas, like in this case. CEA values are elevated in mucinous lesions.