Peri-Hilar Cystic Lymphangioma Mimicking a Biliary Cystic Lesion Causing Biliary Obstruction: A Case Report and Literature Review.

BACKGROUND Lymphangiomas are rare and benign malformations of the lymphatic system. The presentation of intra-abdominal lymphangiomas, especially from within the hepatoduodenal ligament, is rare in the adult population. In this report, we examine a lymphangioma within the hepatoduodenal ligament resulting in biliary obstruction. CASE REPORT A 62-year-old man with surgical history of cholecystectomy presented to the hepatobiliary clinic for a peri-hilar cystic lesion identified on surveillance magnetic resonance imaging (MRI). The patient's MRI revealed a 5.5-cm cystic lesion at the peri-hilar region, likely arising from the biliary tree, which had been increasing in size and causing biliary dilatation. The patient underwent an endoscopic ultrasound, showing a 4.3×2.2 cm cystic structure likley arising from the cystic duct stump with internal septation. An endoscopic retrograde cholangiopancreatography (ERCP) was performed and demonstrated no communication between the biliary tree and the cystic lesion. Given the uncertain etiology of the lesion and its obstructive nature, the patient was moved to the operating room for a complete excision. A well-encapsulated cystic lesion was identified between the cystic duct and the common hepatic duct, which did not communicate with the biliary tree. Pathology confirmed the diagnosis of lymphangioma with features of vascular channel proliferation in the background of fibrotic stroma and lymphoid aggregates. The vascular channel proliferation demonstrated positive immunohistochemical staining for D2-40. At 3-year follow-up, there was no evidence of post-resection recurrence. CONCLUSIONS This case represents an acquired lymphangioma occurring as a sequela of cholecystectomy, likely caused by interruption of the lymphatic drainage system secondary to surgical manipulation.