Hepatic (biliary) cystadenomas are rare multilocular cystic tumors of the liver that are derived from the biliary epithelium and are predominantly located in the right hepatic lobe. These tumors usually involve the hepatic parenchyma (approximately 85% of cases) and occasionally the extrahepatic biliary tract. The size of the tumor is variable and ranges from 1.5-15 cm in diameter; it may weigh as much as 6000 grams.
In 1892, Keen reported the first case of hepatic cystadenoma, which now accounts for 5% of all cystic lesions of the liver.
Hepatic cystadenomas are benign tumors, but they have a high rate of recurrence and a potential for neoplastic transformation in approximately 10% of cases. Removing these tumors and making a proper diagnosis is important, rather than monitoring them as is appropriate for other common benign hepatic tumors, such as focal nodular hyperplasia (FNH), adenoma, and hemangioma.
Hepatic cystadenomas appear as multilocular (rarely unilocular) cystic lesions that are surrounded by a smooth and thick fibrous capsule. The tumors contain numerous internal septations and intraluminal papillary projections, which are lined by mucous-secreting cuboidal or columnar biliary epithelium. This epithelium is sometimes surrounded by a dense mesenchymal stroma containing smooth-muscle cells. A loose layer of collagen-containing blood vessels, nerves, and bile ducts further surrounds this area. True connections with the biliary tree are rare.
Traditionally, cystadenomas are thought to originate from the biliary epithelium, possibly from a congenitally aberrant bile duct. Other possibilities are that the tumors arise directly from embryonic foregut cells or peribiliary endocrine cells.
Two types of hepatic cystadenomas are described pathologically, as follows: mucinous and serous. Mucinous cystadenoma is the predominant type (95% of cases) that occurs in women. They are located in the intrahepatic region (84%), the common bile duct (6%), the hepatic ducts (4%), and the gallbladder (2%).
The etiology of hepatic cystadenomas is unknown.
The resemblance of embryonic structures, such as the gallbladder and the biliary tree, originating from the foregut suggests that these lesions arise from ectopic remnants. The fact that these tumors have been described as early as the first decade of life supports this theory.
Immunohistochemistry and electron microscopy studies have contradicted the possible origin of these tumors from ectopic ovarian tissue.
Environmental factors may play a significant role. Most tumors appear later in life.
The marked female preponderance suggests a role for hormonal influence.
United States data
The prevalence of hepatic cystadenomas is low, with fewer than 200 cases reported in the literature. These tumors account for a very small number of all hepatic tumors.
The true prevalence of hepatic cystadenomas in different areas of the world is unknown.
Race-, sex-, and age-related demographics
The true prevalence of hepatic cystadenomas in different races is unknown.
Most tumors (80-85%) occur in women. The etiology of cystadenoma is unclear, but hormonal involvement is possible.
The peak frequency of hepatic cystadenomas is in patients aged 30-50 years (mean age, 41.7-53.4 y), with two thirds of cases occurring in patients aged 40 years or older. These tumors may arise as early as the first or second decade of life; however, they are extremely rare in children.
The prognosis of hepatic cystadenomas is extremely good if patients undergo a complete surgical resection. Improper treatment, such as marsupialization, internal Roux-en-Y drainage, or percutaneous drainage and alcoholization, is associated with almost certain recurrence. In particular, aspiration or partial excision of cystadenomas is associated with a recurrence rate of higher than 90%
Because of their premalignant potential, untreated lesions carry significant mortality. Some authors report a malignant transformation rate of as high as 20-30%. However, in most series, hepatic cystadenomas carry an extremely low risk of mortality and morbidity after proper surgical resection. 
Complications of hepatic cystadenomas include the following:
Inferior vena cava obstruction