[Diagnostic problems of choledochal cysts in the adult].

Choledochal cysts are rare malformations of the biliary tree, the precise pathogenesis of which remains unclear. The authors present the case of a 21-year-old man with a choledochal cyst and discuss the main issues regarding the diagnosis and treatment of this uncommon lesion. In particular, of all the diagnostic techniques available, magnetic resonance cholangiopancreatography (MRCP) could become the imaging technique of choice for defining the pancreatobiliary ductal anatomy with at least the same degree of accuracy as that of diagnostic ERCP, while avoiding the potential complications associated with the latter. The patient was treated by surgical operation and, after a 12 month follow-up, is disease-free. Surgical treatment is necessary owing to the possibility of malignant transformation.