biliary cystadenomas ( bcas ) are rare , benign , but potentially malignant unilocular or multilocular cystic lesions of the biliary system occurring most commonly in women [ 15 ] . it commonly arises from the liver , but bcas of extra hepatic biliary tract and gall bladder have been reported [ 2 , 69 ] . first publication on bca was in 1887 and the first resection was performed in 1892 . with the widespread availability of modern imaging techniques and developments in safe liver surgery , diagnosis of bca was complicated by the presence of wide variety of cystic lesions in the liver , including simple cysts , parasitic cysts , degenerated metastatic tumours , mucin - producing metastatic tumours , congenital cystic dilatations , cystic hemangioma , lymphangioma , hepatic foregut cysts , mesenchymal hamartoma , and teratoma [ 5 , 1315 ] . due to its premalignant nature and lack of reliability of imaging and preoperative aspiration cytology in differentiating bca from cystadenocarcinoma , all lesions suspected of bca we aim to describe and analyse the outcome following resection of bca from a single tertiary centre . a retrospective analysis of all patients who had resection of bca was carried out from a prospectively maintained liver surgical and pathological database over a period of 21 years ( january 1993 to july 2014 ) . patients ' demographics , clinical presentation , preoperative imaging , operative data and postoperative outcome were analysed . cystic lesions of the liver were evaluated with ultrasound scan , ct scan , and mri liver ( in selected cases ) . cyst characteristics were analysed with respect to number of cysts ( single / multiple ) , locularity ( unilocular or multilocular ) , presence of cyst wall thickening , irregularity , papillary projections , and mural nodule . cystic lesions showing wall thickening , irregularity , internal septations , presence of nodules , papillary projections , and communication with biliary system were offered surgical resection . nonanatomical / segmental resection was performed if feasible , but large bcas and lesions confined to few segments were treated with formal right or left hepatectomy or left lateral segmentectomy . histopathological information regarding completeness of excision , resection margin , and evidence of dysplasia / malignancy were collated . patients who had partial excision of cyst wall for suspected simple cyst and subsequently found to have bca were subjected to formal resection . all patients were followed up in the clinic within 6 weeks of surgery and were reviewed in the clinic if necessary thereafter . patients latest follow - up details were collected from the hospital based computer system and where there was no information available , patient 's general practitioners were contacted regarding patients current clinical status . continuous variables were presented as median with interquartile range and the categorical variables were presented in percentages . median age was 62 ( iq 4874 ) years and all were women except one . the main clinical presentation was abdominal pain ( 74% ) followed by jaundice ( 20% ) , abdominal mass ( 14% ) , and deranged liver function tests ( lfts ) ( 3% ) . one patient was incidentally found to have a cystic lesion in the liver on ultrasound scan performed for irritable bowel syndrome like symptoms . on preoperative imaging , single cyst was seen in majority of the patients ( 76% ) . approximately half of the cysts were unilocular ( n = 15 ) . cyst characteristics were as follows : wall thickening ( 31% ) , wall irregularity ( 38% ) , papillary projections ( 10% ) , and mural nodule ( 3% ) . twenty - six ( 89% ) patients were suspected of having bca on preoperative imaging while the remaining 3 patients were suspected to have simple liver cysts . none of the patients had preoperative cyst fluid cytology , as we believe that negative result will not preclude surgery . surgical procedures performed were as follows : nonanatomical liver resection ( 52% ) , left hemihepatectomy ( 34% ) , right hemihepatectomy ( 10% ) , and left lateral segmentectomy ( 3% ) . three patients had formal reresection following histological confirmation of bca after deroofing of suspected simple liver cysts . the other patient developed bile leak following deroofing of suspected simple liver cyst and required an endoscopic biliary stenting to control the high volume bile leak . two and three patients each developed wound and chest infection , all of which were treated with antibiotics . on pathological examination , the median size of the cyst was 12 ( iq 8.518 )  cm . on histology , 22 patients had typical ovarian / mesenchymal stroma diagnostic of bca and 6 patients had no mesenchymal stroma but were positively stained for mucin . three patients had features of papillary tufting ( ipnb ) with 2 of them also having the presence of ovarian stroma . this was initially treated with percutaneous transhepatic cholangiogram ( ptc ) guided dilatation but eventually required roux - en - y hepaticojejunostomy , 7 years from the primary surgery . one patient died 11 years later due to development of inoperable cholangiocarcinoma at a different site . biliary cystadenomas ( bcas ) are potentially malignant , rare benign cystic lesions of the biliary system of unknown aetiology [ 10 , 23 ] . the incidence of bca is from one in 20,000 to 100,000 people , while the occurrence of cystadenocarcinoma is approximately one in 10 million patients . even though the previously published literature quoted the incidence of bcas to be around 5% of cystic hepatic tumours , the true incidence is still unclear [ 12 , 15 , 24 ] . the controversy is due to lack of established criteria for preoperative diagnosis of unilocular bcas [ 6 , 12 , 14 , 16 ] . due to its potential for malignant transformation and tendency to recur , there is a great concern in treating this tumour with techniques other than formal resection [ 35 ] . proposed a theory of acquired lesion and reported the development of bcas as a reactive process to focal injury [ 3 , 26 ] . it was also suggested that this might have arisen from ectopic embryonal tissue destined to form gall bladder or from ectopic embryonic rest of primitive foregut sequestered within the liver [ 3 , 24 , 27 , 28 ] . presence of endocrine cells in bcas and cystadenocarcinomas also suggest the origin from peribiliary glands . the locules are lined by simple , predominantly columnar epithelium resembling biliary epithelium with cytoplasmic mucin . edmondson initially defined bcas in 1958 as multilocular lesions with ovarian - like stroma , but subsequently bcas without ovarian stroma were reported . due to this uncertainty who , which initially classified these lesions as biliary cystadenoma / adenocarcinoma in 2000 , redefined these lesions as either mucinous cystic neoplasm ( mcn ) or intraductal papillary neoplasm of bile duct ( ipn - b ) depending on the presence of ovarian stroma and papillary growth within the bile duct , respectively [ 3032 ] . who further classified these ipnbs into ipn with low- or intermediate - grade intraepithelial neoplasia , ipn with high - grade intraepithelial neoplasia , and ipn with an associated invasive carcinoma . the majority of biliary cystadenomas do not communicate with the bile ducts , but luminal communication may be occasionally observed . devaney et al . proposed three subsets of cystadenocarcinoma based on the pathology material submitted to their institutional laboratories for primary diagnosis or consultation : ( 1 ) cystadenocarcinoma originating from a benign cystadenoma with ovarian - like stroma occurs exclusively in women ; ( 2 ) de novo cystadenocarcinoma occurs almost only in men ; and ( 3 ) cystadenocarcinoma occurs in women but does not contain an ovarian - like stroma . the development of cystadenocarcinomas is unclear , whether they are de novo cancers or develop from preexisting bcas . however , it is generally believed that they arise from bcas as many cystadenocarcinomas contain areas of bcas in the same sample [ 3 , 24 , 28 , 35 ] . a malignant transformation rate of up to 30% has been reported , and biliary cystadenocarcinoma accounts for 0.41% of malignant hepatic epithelial tumours [ 15 , 16 , 18 , 19 , 36 , 37 ] . elements of bca were present in 1/3 of biliary cystadenocarcinomas [ 5 , 24 ] . wheeler and edmondson reported malignant change in 23% of the resected bcas . in our study none of the patients had malignant change in the final histology of resected bcas . but there were no case - control or cohort studies to define the exact risk of malignant transformation of untreated biliary cystadenoma to cystadenocarcinoma . in the present study also it is unclear , as our patient developed cholangiocarcinoma rather than cystadenocarcinoma many years after the resection of bca . majority of the bcas present with vague abdominal complaints secondary to extrinsic compression of stomach , duodenum , or biliary tree [ 5 , 24 , 38 ] . in our series , but bcas have also been identified in asymptomatic patients during imaging or surgical exploration for unrelated clinical conditions . even with improved imaging techniques , it is still challenging to differentiate bcas from other cystic lesions of the liver . differential diagnosis for bcas includes simple liver cysts , parasitic cysts , haematomas or posttraumatic cysts , liver abscesses , congenital cysts , polycystic disease , caroli 's disease , and neoplastic lesions such as biliary cystadenocarcinoma , undifferentiated embryonal sarcoma , cystic metastasis , metastatic pancreatic or ovarian cystadenocarcinoma , biliary papilloma ( ipnb ) , cystic primary hepatocellular carcinoma , cystic cholangiocarcinoma , and hepatobiliary mesenchymal tumours [ 2 , 32 , 40 , 41 ] . ultrasound scan , ct ( figure 1 ) , mri ( figure 2 ) , mrcp , ercp , intraoperative cholangiography , and choledochoscopy all have been described in the literature for the preoperative work - up of bca [ 4246 ] . preoperative radiological diagnostic accuracy may be as low as 30% , so a high index of suspicion is required in the diagnosis of bca . although radiologic features such as papillary projections , internal septations , wall thickness , irregularities , and mural nodules suggest the possibility of a bca , all of these except papillary projections may be observed in simple cysts as well albeit at a lower frequency [ 48 , 49 ] . cyst fluid ca19 - 9 and cea levels can be helpful to enhance the accuracy of diagnosis of bcas and cystadenocarcinomas from other cystic lesions [ 10 , 17 , 50 ] . however , it is not accurate in differentiating bcas from cystadenocarcinoma , as inadequate sampling may miss the microscopic foci of carcinoma in a cystadenoma [ 5052 ] . preoperative differentiation of bcas from cystadenocarcinoma is extremely difficult and can only be done after pathological examination [ 1 , 3 , 24 , 28 , 39 , 41 ] . fna and needle biopsy may risk dissemination of tumour cells and it is not generally recommended , especially when surgery is planned [ 10 , 52 ] . improper preoperative diagnosis can lead to incorrect and unnecessary procedures such as percutaneous aspiration , ethanol injection , deroofing , and omentoplasty . in our series , 3 patients were diagnosed as simple cysts on imaging but on histological examination were found to be bcas . lewis et al . and madariaga et al . recommended surgical resection as the treatment of choice for all multiloculated hepatic cystic lesions [ 16 , 53 ] . if bca is suspected on imaging , surgery is indicated even if the patient is asymptomatic [ 1 , 24 , 28 , 39 , 52 , 54 ] . the extent of resection remains to be determined , as partial resection with occasional ablation of the residual cyst using electrocautery or argon beam coagulation and/or omentopexy , lobectomy , wedge resection , and enucleation have all been reported [ 16 , 17 , 28 , 29 , 5557 ] . this procedure is a valid alternative where resection is difficult or is likely to be associated with morbidity [ 10 , 14 ] . in our series , patients with large bcas and lesions confined to few segments were treated with formal hepatectomy . other limited procedures like aspiration , fenestration , internal drainage , sclerotherapy , and partial resection are associated with extremely high recurrence ranging from 90 to 100% , compared to 0 to 10% with formal resection [ 4 , 14 , 16 , 20 , 52 , 55 , 5861 ] . in our series , all of our patients had formal resection with no recurrence after a median follow - up of 13 ( iq 6.515.7 ) years . due to its premalignant nature , low radiological diagnostic accuracy , and high recurrence with improper treatment , formal liver resection the prognosis of patients with biliary cystadenoma is good if total excision of the lesion is performed [ 3 , 5 , 14 , 20 , 24 , 52 ] . in the present study the 10-year survival was 90% . only one patient died of late development of cholangiocarcinoma and 2 other patients died of other causes after 8 and 9 years following resection , respectively . we conclude that biliary cystadenomas are rare and can be resected safely with significantly low morbidity .
background . biliary cystadenomas ( bcas ) 
 are rare , benign , potentially malignant cystic lesions of the liver , accounting for less than 5% of cystic liver tumours . 
 we report the outcome following resection of biliary cystadenoma from a single tertiary centre . methods . 
 data of patients who had resection of bca between january 1993 and july 2014 were obtained from liver surgical database . 
 patient demographics , clinicopathological characteristics , operative data , and postoperative outcome were analysed . results . 
 29 patients had surgery for bca . 
 male  :  female ratio was 1  :  28 . 
 clinical presentation was abdominal pain ( 74% ) , jaundice ( 20% ) , abdominal mass ( 14% ) , and deranged liver function tests ( 3% ) . 
 cyst characteristics included septations ( 48% ) , wall thickening ( 31% ) , wall irregularity ( 38% ) , papillary projections ( 10% ) , and mural nodule ( 3% ) . 
 surgical procedures included atypical liver resection ( 52% ) , left hemihepatectomy ( 34% ) , right hemihepatectomy ( 10% ) , and left lateral segmentectomy ( 3% ) . 
 median length of stay was 7 ( iq 6.58.5 ) days . 
 two patients developed postoperative bile leak . 
 no patients had malignancy on final histology . 
 median follow - up was 13 ( iq 6.515.7 ) years . 
 one patient developed delayed biliary stricture and one died of cholangiocarcinoma 11 years later . 
 conclusion . 
 biliary cystadenomas can be resected safely with significantly low morbidity . 
 malignant transformation and recurrence are rare . 
 complete surgical resection provides a cure .