Synchronous Todani types I and III choledochal cysts in a 10-month-old-infant: type IVb
- 112 Downloads
A 10-month-old, previously healthy boy presented with one week of mild jaundice, light-colored stools and irritability. Abdominal sonography showed a large type I choledochal cyst and a separate, distinct cystic mass at the head of the pancreas. Magnetic resonance cholangiopancreatography was performed to evaluate the relationship of the two lesions. A type I choledochal cyst was confirmed, and a coexisting type III choledochocele was identified as the second cystic structure in conjunction with pancreaticobiliary malunion. The infant had complete resection of the type I choledochal cyst with Roux-en-Y hepaticojejunostomy, and anterior duodenotomy with marsupialization of the choledochocele. After five years of follow-up, the child is thriving and has had no recurrence of his symptoms. An exhaustive review of the literature identifies only one previous case of synchronous types I and III choledochal cysts, and this association is not clearly defined among the traditional classifications of type IV multiple choledochal cysts. Because operative management of a type III cyst requires the addition of a transduodenal approach, we encourage accurate reporting of mixed type choledochal cysts for the benefit of surgical planning, epidemiologic tracking and outcomes.
KeywordsTodani Choledochal cyst Choledochocele Magnetic resonance cholangiopancreatography
The Todani classification of choledochal or bile duct cysts recognizes five major types and several subtypes [1, 2]. According to this time-honored classification scheme, nearly 95% of choledochal cysts are type I, and may arise from pancreaticobiliary malunion (PBM) [2, 3, 4, 5, 6]. Type III choledochal cyst, or choledochocele, is found specifically within the intraduodenal segment of the common bile duct. Todani type IV choledochal cysts describe multiple cystic changes of both the intra- and extrahepatic biliary tree (IVa) or of the extrahepatic bile ducts (IVb) exclusively, yet this category of multiple choledochal cystic changes does not clearly include or define choledochoceles among the type IV subtypes [1, 2].
Choledochal cysts are rare and have an estimated incidence between 1 in 100,000 and 150,000 children and are usually discovered on abdominal sonography to evaluate jaundice in infants or abdominal pain in children [7, 8]. Untreated choledochal cysts pose early and late risks associated with biliary obstruction and include recurrent flares of ascending cholangiitis, jaundice, pain and the potential for malignant degeneration of bile duct epithelium or wall [1, 7, 9, 10, 11, 12]. Definitive treatment of types I, II and IV choledochal cysts mandates complete surgical excision of the extrahepatic cyst or its mucosa, and Roux-en-Y hepaticojejunostomy to reconstitute intestinal bile flow . Complex surgical techniques are required for the management of the intrahepatic portion of type IVa bile duct cysts, and further, special operative considerations apply to choledochoceles, which are managed traditionally by transduodenal marsupialization or sphincteroplasty [2, 7, 13, 14]. Given these different anatomical considerations and surgical approaches to the diverse types of choledochal cysts, precise categorization is paramount for operative planning and to track outcomes. Here, we report the unique case of a 10-month-old boy who presented with synchronous, yet discrete types I and III choledochal cysts, an association that has been previously referred to once and is not clearly defined in the Todani classification scheme [1, 2].
A 10-month-old previously healthy boy was admitted to evaluate jaundice, acholic stools and irritability. He was without abdominal mass or peritonitis. Abnormal serum chemistries included: total bilirubin 2.2 mg/dL (direct fraction 1.4), aspartate aminotransferase 145 U/L, alanine aminotransferase 95 U/L, gamma glutamyl transferase 703 U/L, alkaline phosphatase 445 U/L, and lactate dehydrogenase 754 U/L. Complete blood count showed a mild leukocytosis (11.9) without left shift and a hematocrit of 36%. Coagulation profile, amylase and lipase were within normal limits.
Accurate anatomical categorization of patients to a specific Todani type of choledochal cyst is imperative when planning surgical management. Choledochal cyst types I, II, and IVb require complete cyst excision with Roux-en-Y hepaticojejunostomy for reconstruction , and type IVa, similarly requires complete replacement of the extrahepatic cystic bile duct with additional surgical attention to the intrahepatic cystic changes [2, 13, 14]. Type III choledochoceles, however, are preferentially approached through the duodenum [7, 15]. For such lesions, the cyst wall protruding into the duodenal lumen is excised, thereby marsupializing the cyst to eliminate pooling of biliary and pancreatic secretions and to facilitate their intestinal drainage. Given these differing and often complex surgical options for the various subtypes of choledochal cysts, precise preoperative categorization of cases presenting with multiple cystic changes of the bile ducts is useful. Importantly, classification of a choledochal cyst as Todani type IV broadly implies multiple cystic changes of the biliary tree, and further sub-categorization as IVa recognizes both intra- and extrahepatic cysts, whereas IVb restricts cystic changes to the extrahepatic duct [1, 2]. However, neither current subtype of Todani type IV choledochal cysts clearly describes nor accounts for the co-existence of a choledochocele. The co-existence of type I and III choledochal cysts may indeed be a rare variant of Todani type IVb or it may be under-reported. Because the surgical approach to choledochoceles differs from other choledochal cysts, it may be beneficial for surgeons for the Todani classification scheme to have a separate sub-category: type IVc, “C” for choledochocele. This anatomic specificity in categorization would aid the surgeon in operative preparation, epidemiologic tracking and family counseling. If broader recognition of these mixed type cysts existed in the literature, the surgical community could consider adding this third subtype to the Todani mixed type IV category that would signify more clearly the presence of a choledochocele.
The concurrent presentation of Todani types I and III choledochal cysts in early infancy is additionally thought provoking from a developmental perspective, as each alone is thought to arise from distinct embryologic events [2, 3, 4, 6]. The prevailing theory surrounding the developmental etiology of types I and IV choledochal cysts describes an anomalous pancreaticobiliary duct union yielding a “long common channel”, which in turn imparts a relative obstruction to the normal flow of pancreatic and biliary juices through the common duct. Over time, this obstruction theoretically increases luminal pressure and prolongs exposure of ductal epithelia to digestive enzymes, thereby inciting chronic mural inflammation and a weakening of duct wall integrity [3, 4]. In contrast, choledochoceles are typically found within the duodenal wall, and are thought to develop either from anomalous congenital insertion of the common bile duct into the sphincteric complex of, or from chronic obstruction at, the ampulla .
An exhaustive review of the literature identifies only one prior reference of types I and III choledochal cysts arising in the same patient, only briefly alluded to in the context of the original Todani case series . No report is found to date that suggests the two cysts share a common embryological basis, nor have type III cysts routinely been associated with pancreaticobiliary malunion. Because of the theorized differing etiologies of these two distinct bile duct cysts, the synchronous presentation of both lesions is unique. Moreover, the occurrence of either lesion alone in a young infant implies a congenital origin, while the concurrence of both, in conjunction with PBM, may signal a potentially unifying embryologic etiology. Precise anatomic categorization is key to better understanding the pathogenesis of synchronous types I and III bile duct cysts. Our finding of a type I choledochal cyst concurrent with a type III choledochocele should remind surgeons of the possibility of mixed type bile duct cysts and emphasize the importance of complete pre-operative anatomic evaluation utilizing several imaging modalities.
In summary, the synchronous presentation of both type I and III bile duct cysts, or type IVb, in our infant represents the first time that this specific mixed-type choledochal cyst has been reported in the literature with long-term follow-up. Preoperative recognition of this unique concurrence of anatomically disparate bile duct cysts aided surgical planning and family consultation. Surgical management of this novel, mixed bile duct cyst required both total excision of the type I component, including mucosectomy of its intrapancreatic portion, with Roux-en-Y hepaticojejunostomy, and transduodenal marsupialization of the choledochocele. Our approach maintains normal biliary and pancreatic flow and thus minimizes the risk for ascending cholangitis, ductal lithiasis, and malignant degeneration. Although our infant is well and asymptomatic 60 months after operation, longer follow-up is necessary to determine the efficacy of this approach. The presence of PBM in this infant having both Todani type I and III cysts may provide evidence for a common embryopathy, in contrast to previously held views. More patients with this novel mixed-type choledochal cyst need to be identified and evaluated for PBM before claiming a shared congenital origin. Given the rarity of type III cysts in infants and the novelty of its concurrence with the classic type I variant, definitive management recommendations should remain consistent with those established for the respective anomaly.
- 6.Babbitt DP (1969) Congenital choledochal cysts: new etiological concept based on anomalous relationships of the common bile duct and pancreatic bulb. Ann Radiol (Paris) 12(3):231–240Google Scholar