An 8-year-old boy is brought to the emergency department due to worsening abdominal pain for a day. He has vomited twice but has had neither fever nor diarrhea. The patient has had no previous abdominal pain or trauma. Vital signs are unremarkable. Examination shows scleral icterus and epigastric tenderness. An abdominal mass is palpable in the right upper quadrant. Laboratory results are as follows:
| Bilirubin, total | 6.5 mg/dL |
| Bilirubin, direct | 3.4 mg/dL |
| Amylase | 138 U/L |
| Lipase | 152 U/L (normal: 3-43) |
Ultrasonography reveals an extrahepatic cystic mass and a normal gallbladder. Which of the following is the most likely underlying cause of this patient's presentation?
Biliary cyst | |
Pathogenesis |
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Presentation |
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Diagnosis |
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Complications |
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*Often, only two-thirds of findings are present. MRCP = MR cholangiopancreatography; RUQ = right upper quadrant. | |
This patient has acute abdominal pain, vomiting, and elevated amylase and lipase, findings consistent with acute pancreatitis. The most likely underlying cause of pancreatitis in an otherwise healthy child with an extrahepatic cystic mass is a biliary cyst, a dilation of the biliary tree that most commonly involves the common bile duct (CBD).
The presentation of biliary cysts is variable and includes the following:
Biliary cysts increase the risk for pancreatitis due to their association with an anomalous pancreaticobiliary junction, which is characterized by an abnormally long, common channel connecting the pancreatic duct and CBD outside the duodenum. This lengthy channel is predisposed to obstruction from plugs and stones, which can lead to reflux of pancreatic fluid, as well as cholestasis (eg, conjugated hyperbilirubinemia).
(Choice A) Biliary atresia presents in early infancy with obstructive jaundice (eg, acholic stools, dark urine) due to fibroobliteration of the extrahepatic biliary tree, including the gallbladder. This child's age, palpable abdominal mass, and normal gallbladder are inconsistent with this diagnosis.
(Choice C) Carcinoma of the pancreatic head can cause obstructive jaundice and a nontender, palpable mass related to an enlarged gallbladder (eg, Courvoisier sign). However, this cancer almost always develops in adults and is exceedingly unlikely in a young child.
(Choice D) Focal nodular hyperplasia, a solid liver lesion usually seen in women, not children, is typically asymptomatic but may cause right upper quadrant pain. Scleral icterus, hyperbilirubinemia, and an extrahepatic mass do not occur.
(Choice E) Pancreatic pseudocyst, which may cause abdominal pain, vomiting, and, sometimes, elevated bilirubin and lipase levels, develops slowly over several months in patients with a history of either acute or chronic pancreatitis. The acute onset of symptoms in this patient makes pancreatic pseudocyst unlikely.
Educational objective:
Biliary cysts, or congenital dilations of the biliary tree, can initially present with complications, such as cholestasis and pancreatitis due to distal biliary obstruction, leading to a reflux of bile and pancreatic fluid.