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Spontaneous Biliary Perforation: Biloma Resembling a Small Bowel Duplication Cyst

2000; Lippincott Williams & Wilkins; Volume: 31; Issue: 2 Linguagem: Inglês

10.1097/00005176-200008000-00024

1536-4801

David S. Goldberg, David Rosenfeld, Sharon Underberg‐Davis,

Congenital Anomalies and Fetal Surgery

Spontaneous biliary perforation (SBP) in infancy is rare, with fewer than 140 cases reported to date. The cause of SBP of the extrahepatic biliary system remains unknown. Biliary duct malformation, infection, obstruction, trauma, and other causes have been postulated. We report a case of SBP in a 2-month-old boy with atypical imaging features including a biloma of the lesser sac resembling a gastrointestinal duplication cyst and a false-negative hepatobiliary scan. During surgery, he was found to have a perforation at the junction of the cystic and common ducts that caused a biloma of the lesser sac. To date, this radiologic picture has not been reported. CASE REPORT A 2-month-old boy was brought to our center for treatment of vomiting and diarrhea of 5 days' duration as well as a low-grade fever. Physical examination revealed a soft, nontender, nondistended abdomen. Laboratory values included white blood cell count, 25,000/mm3; total bilirubin level, 5.1 mg/dL; γ-glutamyl transpeptidase (GGT), 899 U/L; alanine aminotransferase (ALT), 11 U/L; aspartate aminotransferase (AST), 21 U/L; and alkaline phosphatase, 223 U/L. Ultrasound showed a 5-mm echogenic focus in the common hepatic duct that was thought to represent a sludge ball with evidence of intrahepatic duct, common hepatic duct, and common bile duct dilatation. Computed tomographic (CT) scan demonstrated a large cystic mass in the left upper quadrant posterior to the stomach in the region of the lesser sac. Additional multiple smaller cysts were present in the porta hepatis (Fig. 1). A hepatobiliary scan showed no evidence of biliary leakage (Fig. 2). Before surgery, a diagnosis of enteric duplication cyst causing secondary biliary obstruction was entertained.FIG. 1.: Computed tomographic scan demonstrates a large left upper quadrant biloma in the vicinity of the lesser sac (short arrows) displacing the stomach medially (S). Additional small bilomas (long arrows) are present in the porta hepatis.FIG. 2.: Hepatobiliary scan demonstrates no evidence of biliary leakage.Laparotomy revealed the cystic mass to be a biloma in the lesser sac. An intraoperative cholangiogram demonstrated a normal gallbladder and patent cystic duct. Dilated intrahepatic biliary radicles were identified. Extravasation of contrast into the porta hepatis confirmed an SBP (Fig. 3). In addition, injection of saline into the biliary system after the biloma was opened showed a communication with the biloma at the level of the junction of the cystic duct and biliary tree. Cholecystostomy and external drainage of the biliary perforation were performed. Bile drained through a Blake drain for 4 weeks until a follow-up cholangiogram demonstrated no evidence of extravasation.FIG. 3.: Intraoperative cholangiogram demonstrates contrast opacification of the common biliary tree and radicles, with extravasation into the porta hepatis (arrows).DISCUSSION Our review of the available literature showed that fewer than 140 cases of spontaneous extrahepatic biliary perforation have been reported since the first case report in 1932 by Dijkstra (1). This entity occurs almost exclusively in neonates. Although the pathogenesis of spontaneous perforation of the biliary ducts remains unknown, suspected causes reported include congenital pancreaticobiliary anomalies, cholelithiasis, infection, pancreatitis, trauma, and abnormal bile (2). The most widely accepted cause remains a congenital localized mural malformation occurring during embryogenesis (2,3). The location of the perforation in almost all cases occurs at the union of the cystic and common ducts. This general concept has also been advanced for the pathogenesis of choledochal cyst (4–7). A small area of weakness may lead to rupture, whereas a more extensive area may gradually dilate and form a choledochal cyst (6). To our knowledge, there have been no reports of this disease's resulting in a biloma resembling an intestinal duplication cyst. Common bile duct obstruction due to stones or ductal stenosis have been reported in patients with SBP. Both could cause an increase in biliary tract pressure and dilatation and, in theory, could result in rupture at the defective part of the bile duct wall. From another viewpoint, the stones or sludge may in fact be the result rather than the cause of perforation by forming in the temporarily dysfunctional common bowel duct distal to the perforation (6). This area is highly controversial. The initial symptoms are typical for this condition. During the first few weeks of life, the infants are typically normal. Shortly thereafter, irritability, failure to thrive, increasing ascites, abdominal distension, and mild jaundice become apparent. Except for elevated bilirubin, the liver function tests are usually normal, a feature that helps differentiate this condition from neonatal hepatitis (8). Although the initial symptoms in our patient were consistent with the usual subacute presentation of SBP, the imaging findings were misleading. Diagnosis of ascites can be made radiologically by a combination of ultrasonography and CT. Determination of whether the ascites is biliary in origin is made by hepatobiliary scintigraphy. Ultrasound and CT typically show biliary ductal dilatation and ascites or a fluid collection regional to the gallbladder or common bile duct. Characteristic scintigraphic findings are leakage of bile into the peritoneal cavity, usually confirmed by intraoperative cholangiogram. With recent advancements in hepatobiliary scintigraphy, there has been an extremely high correlation between SBP and a positive demonstration of bile leakage by hepatobiliary scan. In a review of the current literature, we noted 18 of 19 cases (not including this case) in which biliary leakage was demonstrated by hepatobiliary scintigraphy before surgery, during which the leakage was confirmed by intraoperative exploration. There were two confounding aspects to our case. First, there was a false-negative hepatobiliary scan. This finding is highly atypical; current literature supports a very high specificity and sensitivity (as high as 100% in one series) for demonstration or exclusion of leakage. We hypothesized one cause of the negative hepatobiliary scan to be that the biliary leak sealed itself over before the scan was performed. The other equally misleading finding was the location of the cystic mass in the lesser sac region posterior to the stomach: Biloma has never been described in this region. Previous reports have confined the biloma to the porta hepatis and gallbladder fossa. Although the diagnosis of SBP was entertained, these atypical findings suggested alternative possibilities. The fluid collection in the left upper quadrant was thought to represent an enteric duplication cyst with additional satellite cysts in the porta hepatis producing biliary obstruction. Early surgical treatment (before infection sets in) is preferred, because the condition may be fatal if untreated (6,8,9). In most instances, simple drainage followed by spontaneous closure is all that is necessary in surgery. Exploration of the porta hepatis should not be routinely performed, because the inflammatory nature of this process makes it technically hazardous. Healing time is approximately 4 weeks (supported by our case) and is usually accompanied by antibiotic administration. Morbidity and mortality are very low if treatment is proper. Pediatric radiologists should be aware of SBP. The presence of a loculated biloma in the left upper quadrant that stimulates formation of a gastric duplication cyst and absence of biliary leakage on hepato-iminodiacetic acid (HIDA) scan are emphasized in this report.