Retroperitoneal mesothelial cyst misdiagnosed as a congenital choledochal cyst for an infant patient: A case report and literature review

INTRODUCTION: Mesothelial cyst (MC) is very uncommon in clinic, which could occasionally occur in peritoneal, retroperitoneal or even pleural cavity. PRESENTATION OF CASE: We hereby described an infant patient with retroperitoneal MC who was misdiagnosed as congenital choledochal cyst by both radiologists and clinicians. A choledochal cyst resection with hepatojejunostomy under the da Vinci surgical system was routinely prepared for this patient but a local resection for the whole lesion was unexpectedly performed during the operation. The diagnosis of retroperitoneal MC was confirmed by the pathological analysis from surgical specimens. DISCUSSION: MC in small size is usually asymptomatic and sometimes detected by imaging examinations which manifests a well-boundary, watery-density and cystic lesion with no enhancement and is often misdiagnosed as lymphangioma or pancreatic pseudocyst. For pediatric patients, MC can occur in the diaphragm and liver in the literature, while retroperitoneal MC around hepatoduodenal ligament for an infant has never been mentioned before. We reported the first case of a retroperitoneal MC around hepatoduodenal ligament for an infant who was preoperatively misdiagnosed as choledochal cyst surgically treated by the da Vinci surgical system. CONCLUSION: Retroperitoneal MC around hepatoduodenal ligament should also be considered and resected for an infant.