Figure 1
ERCP, annular pancreas
The 2 mm long stricture of the common bile duct with prestenotic dilatation.
Clinical History
For six years the patient occasionally noticed having light yellow colored skin. For the last year pressure in the upper abdomen after meals, especially in the afternoon was the main symptom and was worsened after fatty food. She never vomitted, had no diarrhea or elevated temperature.
Imaging Findings
For six years the patient occasionally noticed having light yellow colored skin. For the last year pressure in the upper abdomen after meals, especially in the afternoon was the main symptom and was worsened after fatty food. She never vomitted, had no diarrhea or elevated temperature. Difficulties gradually increased and 6 months ago she underwent the first US examination. A concrement, a few mm in size, was found in the infundibulum of the gallbladder. The hepatic and common bile ducts were widened up to 1 cm above the ampulla of Vater. The cause of dilatation was not clear.
3 months after US examination the patient presented at the emergency department because of abdominal pain, vomiting and jaundice. Blood tests of liver function were abnormal, but normal lipase and amylase were found. Thick gallbladder wall, but no concrement, was found on US examination.
At ERCP a 2 mm long stricture of the common bile duct with prestenotic dilatation was found, and dilatation of the hepatic and cystic ducts (fig 1). The pancreatic duct opened into the common ampulla and had a normal course. There was no accessory pancreatic duct visible. Endoscopic US confirmed a benign stenosis (Fig. 2).
At intraoperative cholangiography, an almost complete obstruction of common bile duct was found at the site described by US. It was caused by a narrow band of pancreatic tissue encircling the common bile duct.
3 months after US examination the patient presented at the emergency department because of abdominal pain, vomiting and jaundice. Blood tests of liver function were abnormal, but normal lipase and amylase were found. Thick gallbladder wall, but no concrement, was found on US examination.
At ERCP a 2 mm long stricture of the common bile duct with prestenotic dilatation was found, and dilatation of the hepatic and cystic ducts (fig 1). The pancreatic duct opened into the common ampulla and had a normal course. There was no accessory pancreatic duct visible. Endoscopic US confirmed a benign stenosis (Fig. 2).
At intraoperative cholangiography, an almost complete obstruction of common bile duct was found at the site described by US. It was caused by a narrow band of pancreatic tissue encircling the common bile duct.
Discussion
Annular pancreas is an uncommon congenital anomaly. At autopsy, the incidence has been reported between 1 to 3 per 20000. At ERCP the diagnosis of annular pancreas was confirmed in as many as one in 150 patients undergoing this procedure. It may manifest clinically in the neonate (52%) or remain silent until adulthood (48%).
In neonates, the symptom of severe duodenal obstruction is vomiting on the first day of life. There is often previous history of polyhydramnion. A number of other anomalies such as intestinal malrotation, duodenal atresias, and cardiac anomalies are often present as well.
In adults, symptoms of annular pancreas usually occur between the ages of 20-50 years as a duodenal obstruction, rarely as a biliary tract obstruction.
In older children and adults, nausea, vomiting, and epigastric pain are the main complaints of duodenal obstruction. The incidence of gastric and duodenal ulcers ranges from 26% to 48%, and pancreatitis develops in 15% to 30% of patients. The obstruction of the duodenum is usually not sufficient to cause symptoms unless peptic ulcer disease or pancreatitis develop.
Annular pancreas is the cause of extrahepatic biliary obstruction in the absence of pancreatitis. Complete obstruction to the outflow of bile produces back pressure throughout the entire biliary system and damage to the interlobular bile ducts. The injury leads to an inflammatory reaction and biliary cirrhosis.
Although an upper GI series is considered the diagnostic test for annular pancreas encircling the duodenum, recognition of annular pancreas encircling biliary tract is not always made preoperatively.
When there is no visible duct in the pancreatic ring around the bile duct, when the duct in annular pancreas does not empty into the main pancreatic duct or it is obstructed, it is even not possible to make the diagnosis with ERCP.
In neonates, the symptom of severe duodenal obstruction is vomiting on the first day of life. There is often previous history of polyhydramnion. A number of other anomalies such as intestinal malrotation, duodenal atresias, and cardiac anomalies are often present as well.
In adults, symptoms of annular pancreas usually occur between the ages of 20-50 years as a duodenal obstruction, rarely as a biliary tract obstruction.
In older children and adults, nausea, vomiting, and epigastric pain are the main complaints of duodenal obstruction. The incidence of gastric and duodenal ulcers ranges from 26% to 48%, and pancreatitis develops in 15% to 30% of patients. The obstruction of the duodenum is usually not sufficient to cause symptoms unless peptic ulcer disease or pancreatitis develop.
Annular pancreas is the cause of extrahepatic biliary obstruction in the absence of pancreatitis. Complete obstruction to the outflow of bile produces back pressure throughout the entire biliary system and damage to the interlobular bile ducts. The injury leads to an inflammatory reaction and biliary cirrhosis.
Although an upper GI series is considered the diagnostic test for annular pancreas encircling the duodenum, recognition of annular pancreas encircling biliary tract is not always made preoperatively.
When there is no visible duct in the pancreatic ring around the bile duct, when the duct in annular pancreas does not empty into the main pancreatic duct or it is obstructed, it is even not possible to make the diagnosis with ERCP.
Differential Diagnosis List
Annular pancreas
Final Diagnosis
Annular pancreas
References
[1]
Benger JR, Thompson MH.
Annular pancreas and obstructive jaundice.
Am J Gastroenterology. 1997 Apr; 92(4):713-14. (PMID: 9128338)
[2]
Dharmsathaphorn K, Burrel M, Dobbins J.
Diagnosis of anular pancreas with endoscopic retrograde cholangiopancreatography.
Gastroenterology. 1979 Nov; 77(5):1109-14. (PMID: 488638)
[3]
Clifford KMA.
Annular pancreas diagnosed by endoscopic retrograde-choledocho-pancreatography (ERCP).
Br J Radiol. 1980 Jun; 53(630):593-595. (PMID: 7426874)
[4]
Tolia V, Ramachandra R, Klein M.
Annular pancreas.
J Pediatr. 1997 Jul; 131(1 Pt 1 ):14-15. (PMID: 9255186)
[5] Shirkhoda A. <br>Anomalies and anatomic variants of pancreas. <br>In Gore RM, Levine MS (eds) Textbook of gastrointestinal radiology. <br>WB Saunders, Philadelphia, pp 1754-1766 (2000).
Case information
| URL: | https://www.eurorad.org/case/2176 |
| DOI: | 10.1594/EURORAD/CASE.2176 |
| ISSN: | 1563-4086 |
Figure 2
Endoscopic ultrasonography, annular pancreas
A benign stenosis of the bile duct with prestenotic dilatation.
ERCP, annular pancreas
The 2 mm long stricture of the common bile duct with prestenotic dilatation.
Endoscopic ultrasonography, annular pancreas
A benign stenosis of the bile duct with prestenotic dilatation.