Pancreatic developmental biliary cyst

A 44-year-old woman presented with a pancreatic cystic lesion detected during a routine physical examination. She had no significant medical history or family history. Laboratory investigations were unremarkable, with preoperative cancer antigen 19-9 (CA19-9) at 24.8 U/mL and carcinoembryonic antigen (CEA) at 2.6 ng/mL. Computed tomography (CT) demonstrated an ovoid, hypodense lesion within the pancreatic body, measuring approximately 6.5 cm × 5 cm ×2.5 cm. On contrast-enhanced imaging, the lesion showed no enhancement, and no pancreatic or biliary ductal dilatation was observed (Figure 1A,1B). Endoscopic ultrasound (EUS) detected a cyst with moderate echogenicity, heterogeneous internal echoes, a honeycomb-like structure, smooth margins, and no communication with the pancreatic duct, suggesting a pancreatic cystadenoma (Figure 1C). Given the size of the cyst, the patient underwent a spleen-preserving distal pancreatectomy. Histopathological examination revealed a smooth cystic wall lined by bile duct-like epithelium, containing caseous material within the cyst. The cyst wall exhibited areas of thickened smooth muscle and glandular structures resembling bile ducts, surrounded by normal pancreatic tissue (Figure 1D). The lesion was diagnosed as a developmental malformation of a biliary cyst within the pancreas. The patient recovered well from the surgical procedure, with no abnormalities detected at a 1-year follow-up. To our knowledge, this is the first reported case of a developmental biliary cyst malformation occurring within the pancreas.

Figure 1 CT, EUS, and histopathological analyses of the pancreatic lesion (red arrows). (A,B) Enhanced CT reveals a large cystic lesion in the pancreatic body near the splenic vein. (C) EUS image. (D) HE. CT, computed tomography; EUS, endoscopic ultrasound; HE, hematoxylin-eosin.

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