Biliary cystadenoma and cystadenocarcinoma overview

# Overview
Biliary cystadenoma is an uncommon unilocular or multilocular cystic neoplasm that usually arises in the liver or occasionally in the extrahepatic biliary tree and gallbladder. Biliary cystadenomas constitute less than 5% of cystic lesions of the liver. On gross pathology, biliary cystadenoma is unilocular or multilocular cystic lesion filled with fluid or blood. Cystic fluid may be clear and mucinous. On microscopic histopathological analysis, presence of biliary-type epithelium wall supported by ovarian-like stroma is characteristic finding of biliary cystadenoma. The cause of biliary cystadenoma has not been identified. However, it is thought to occur either as a result of the development of ectopic foci of primitive foregut sequestered within the liver or due to the obstruction of the congenitally aberrant bile duct. Neoplastic transformation to cystadenocarcinoma is the most common complication of biliary cystadenoma. Biliary cystadenoma with mesenchymal stroma is associated with most favorable prognosis. Symptoms of biliary cystadenoma include abdominal pain in right upper quadrant, abdominal distension, abdominal mass, nausea, and vomiting. Common physical examination findings of biliary cystadenoma are a palpable, tender mass in the right upper quadrant of abdomen or epigastrium, jaundice, and ascites. On ultrasound, biliary cystadenoma is characterized by fluid filled multiloculated cyst with enhanced transmission. The cyst fluid may contain low level echoes from blood products, mucin, or proteinaceous fluid. Contrast-enhanced ultrasound demonstrates minimal enhancement since the tumors are largely avascular. Surgical resection of tumor is the mainstay of treatment for biliary cystadenoma. Complete enucleation of the cyst is a safe and effective treatment for biliary cystadenoma and hepatic resection is a suitable treatment option for biliary cystadenocarcinoma.

# Classification
There is no classification system established for biliary cystadenoma and biliary cystadenocarcinoma.

# Pathophysiology
On gross pathology, biliary cystadenoma is unilocular or multilocular cystic lesion filled with fluid. Cystic fluid may be clear and mucinous. On microscopic histopathological analysis, presence of biliary-type epithelium wall, occasional papillary projections, and ovarian-like stroma are characteristic findings of biliary cystadenoma.

# Causes
The cause of biliary cystadenoma has not been identified. However, it is thought to occur either as a result of the development of ectopic foci of primitive foregut sequestered within the liver or due to the obstruction of the congenitally aberrant bile duct.

# Differential Diagnosis
Biliary cystadenoma and cystadenocarcinoma must be differentiated from simple liver cysts, liver hematoma, hepatic echinococcal cyst, hepatic abscess, post-traumatic cysts, and bilomas.

# Epidemiology and Demographics
Biliary cystadenoma is a rare disease. Females are more commonly affected with biliary cystadenoma than males. The median age at diagnosis of biliary cystadenoma is 45 years.

# Risk Factors
There are no established risk factors for biliary cystadenoma.

# Screening
According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for biliary cystadenoma.

# Natural History, Complications and Prognosis
Common complication of biliary cystadenoma include neoplastic transformation to biliary cystadenocarcinoma. Biliary cystadenoma with mesenchymal stroma is associated with most favorable prognosis.

# Diagnosis

## Staging
There is no established system for the staging of biliary cystadenoma and biliary cystadenocarcinoma.

## History and Symptoms
Symptoms of biliary cystadenoma include abdominal pain in right upper quadrant, abdominal distension, abdominal mass, nausea, and vomiting.

## Physical Examination
Common physical examination findings of biliary cystadenoma are a palpable, tender mass in the right upper quadrant of abdomen or epigastrium, jaundice, and ascites.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of biliary cystadenoma include elevation of serum alkaline phosphatase, serum bilirubin, and CA 19-9 in cystic fluid. Some patients with biliary cystadenoma may have leukocytosis with left shift, which is usually suggestive of superinfection of the tumor.

## CT
On CT scan, biliary cystadenoma is characterized by fluid filled multiloculated cyst with calcification of septa and cyst wall. The appearance of the cyst fluid on CT is variable depending on its composition.

## MRI
Abdominal MRI may be helpful in the diagnosis of biliary cystadenoma, which demonstrates variability on T1-and T2-weighted images.

## Ultrasound
On ultrasound, biliary cystadenoma is characterized by fluid filled multiloculated cyst with enhanced transmission. The cyst fluid may contain low level echoes from blood products, mucin, or proteinaceous fluid. Contrast-enhanced ultrasound demonstrates minimal enhancement since the tumors are largely avascular.

# Treatment

## Medical Therapy
There is no medical therapy for biliary cystadenoma and cystadenocarcinoma. The mainstay of therapy is surgical resection.

## Surgery
Surgical resection of tumor is the mainstay of treatment for biliary cystadenoma. Complete enucleation of the cyst is a safe and effective treatment for biliary cystadenoma and hepatic resection is a suitable treatment option for biliary cystadenocarcinoma.