Pancreatic Mucinous Cystic Neoplasm

A 47-year-old woman presents with vague upper abdominal discomfort. CT imaging reveals a 7-cm cystic lesion in the pancreatic body-tail. The structure marked **A** in the diagram—a unilocular thick-walled cyst with peripheral eggshell calcification and no communication with the main pancreatic duct—is identified on EUS-guided cyst aspiration to contain elevated CEA (>800 ng/mL), low amylase, and viscous mucinous material. Histology demonstrates columnar mucinous epithelium with an underlying densely cellular ovarian-type stroma. Based on these imaging and pathological findings, what is the most appropriate management?