biliary cast syndrome is defined as the presence of casts within the intra- and/or extrahepatic bile ducts , causing obstruction and cholangitis , eventually complicated by multiple strictures , ductal dilation , and/or liver microabscesses.1,2 this is an uncommon condition , but is more frequently described in liver transplant patients.3,4 only a few reports have described biliary cast syndrome in nonliver transplant patients ; these included patients with antiphospholipid antibody syndrome , b - cell non - hodgkin lymphoma , cholecystectomy , and those who had undergone allogeneic hematopoietic stem cell transplantation.4 - 10 the exact pathogenesis of biliary casts remains uncertain ; however , many factors have been suggested as playing an etiological role in their formation . theoretically , anything that increases viscosity and/or hinders the flow of bile may precipitate cast formation . therefore , biliary sludge is known to be a prerequisite for cast formation.4 here we present one case of biliary cast syndrome , which developed in a nonliver transplant patient who had biliary sludge for a long period of time , providing evidence that long - standing biliary sludge may lead to cast formation .
an 80-year - old man was admitted with a complaint of abdominal pain and fever .
the patient 's history included brain surgery due to head trauma approximately 1 year ago ; he had remained in a bed - ridden state since then .
the patient had a blood pressure of 109/66 mm hg , a heart rate of 122 beats / min , a respiration rate of 30 breaths / min , and a body temperature of 38.4. physical examination revealed tenderness at right upper quadrant of abdomen .
laboratory examination revealed a hemoglobin of 14.2 g / dl ( normal range , 13 to 17 ) ; white blood cell , 29,900/mm ( normal range , 4,000 to 10,000 ) ; platelet , 296,000/mm ( normal range , 130,000 to 350,000 ) ; total bilirubin , 2.5 mg / dl ( normal range , 0.22 to 1.2 ) ; aspartate aminotransferase ( ast ) , 742 iu / l ( normal range , < 40 ) ; alanine aminotransferase ( alt ) , 422 iu / l ( normal range , < 40 ) ; alkaline phosphatase ( alp ) , 1,593
iu / l ( normal range , 66 to 220 ) ; and -glutamyl transpeptidase 1,321
we performed percutaneous transhepatic cholecystostomy for the purpose of immediate decompression of the biliary tract .
follow - up tubography via percutaneous cholecystostomy showed multiple tubular filling defects in the extrahepatic bile duct ( fig .
endoscopic retrograde cholangiopancreatography ( ercp ) revealed the same features ; therefore , we performed endoscopic sphincterotomy followed by basket retrieval of the black colored tubular structures from the extrahepatic bile duct ( fig .
histology of the biliary tubular structures showed aggregates of bile pigmented amorphous materials , consistent with biliary cast ( fig .
currently , almost 16 months after the removal of the biliary cast , he was found to be asymptomatic and maintained a normal range of liver biochemistries .
one year before admission , he had suffered head trauma after falling from his bicycle .
he underwent emergent brain surgery , followed by management in the intensive care unit ( icu ) for several weeks .
after that , he was stable but remained in a bedridden state . at approximately 1 month after the brain surgery , his liver biochemistry , which had remained in the normal range since admission , began to deteriorate : a bilirubin of 0.5 mg / dl , ast of 51
iu / l , alt of 92 iu / l , alp of 361 iu / l , and -glutamyl transpeptidase of 525 iu / l .
we performed an investigation of possible causes for abnormal liver biochemistry , such as drugs , viral infections , and etc .
however , an abnormal ultrasonographic finding , gallbladder distention filled with a large amount of sludge , was proven to be the only cause of abnormal liver biochemistry ( fig .
, the patient did not show acute cholangitis ; in addition , he maintained stable vital signs and had no complaints .
considering the poor general status with bed - ridden state , he received only supportive care with intermittent blood tests .
5 shows the patient 's liver biochemistry during the past year , showing wax and wane , with constant deterioration , since 4 months before developing acute cholangitis and being admitted to the hospital .
pathophysiology of biliary cast formation is unclear ; however , hepatic infarction , fasting related gall bladder hypocontractility , biliary infection , biliary ischemia due to hypotension induced sepsis , bile pigment load due to absence of a gallbladder after cholecystectomy , and benign biliary stricture are included in suggested factors for biliary cast formation in nonliver transplant patients.4 - 10 these conditions are eventually predisposed to hindrance of bile flow , and thereby result in biliary sludge formation . this case provided evidence to demonstrate that the presence of long - standing biliary sludge may lead to development of biliary casts .
we initially noticed gallbladder sludge in the patient at about 1 month after brain surgery .
development of gallbladder sludge can be explained by the brain surgery and an icu setting , which both appear to be recognized risk factors for sludge formation due to gallbladder hypocontractility.11 the gallbladder sludge then migrated into the bile duct over a long period of time , which can be explained indirectly by long - standing and gradually increased abnormal liver biochemistry ; biliary cast formation might then have developed and was observed as acute cholangitis in the present case .
there is no recommended standard management protocol for removal of biliary casts and each case should be viewed individually .
although data are limited , five of eight nonliver transplant patients ( table 1 ) underwent successful removal of biliary casts by ercp only .
therefore , ercp is thought to be a reasonable step to take prior to considering laparotomy , particularly in nonliver transplant patients .
however , reports on liver transplant patients showed that endoscopic management was still effective only in 25% of liver transplant patients with cast formation and that many patients experiencing endoscopic treatment required retransplantation.12,13 in conclusion , our case is a great example of biliary cast syndrome , showing that long - standing biliary sludge may lead to cast formation .
 development of biliary casts is very unusual , especially in patients who have not undergone liver transplantation . 
 variable causes of biliary cast formation in nonliver transplantation patients have been suggested . 
 however , stasis of bile flow and/or gallbladder hypocontractility is known to eventually result in the promotion of biliary sludge and subsequent cast formation . here 
 we present one case of biliary cast syndrome , which developed in a nonliver transplant patient who had biliary sludge for a long period of time , providing evidence that long - standing biliary sludge may lead to cast formation . 
INTRODUCTION
CASE REPORT
DISCUSSION