Imaging findings of mucinous hepatobiliary cystadenoma

Clinical History

Abdominal pain and discomfort.

Imaging Findings

The patient underwent abdominal US that revealed, in the right lobe of the liver, the presence of a large cystic mass (25 x 16 x 16 cm in size) with regular contours and dense fluid content (Fig. 1).
Subsequent abdominal CT scan confirmed the presence of a large, well-defined cystic mass (26 x 17 x 15 cm in size) with few irregular, internal septations and rare thin wall calcifications. On enhanced CT images a moderate enhancement of the internal septations and cystic wall without mural nodule was observed (Fig. 2).
Surgical excision was performed and histological examination of the specimen revealed that the cyst was lined of a single layer of cuboidal epithelium, surrounded by an ovarian stroma with rare calcifications. Immunohistochemistry showed an expression of cytokeratin 7 in epithelial cells and oestrogen receptor and progesteron receptor in stromal cells. The histological and immunohistochemical findings confirmed the diagnosis of mucinous hepatobiliary cystadenoma.

Discussion

Mucinous hepatobiliary cystadenoma is a rare cystic neoplasm that usually arises in the liver or in the extra-hepatic bile ducts and may show malignant degeneration into cystadenocarcinoma. This lesion tends to occur more often in middle-aged women and accounts for less than 5% of all hepatic cysts [1]. Biliary cystadenomas range in diameter from 1.5 to 35 cm.
Patients are usually asymptomatic, but in the case of large tumours they may present a palpable mass, intermittent pain or biliary obstruction [2].
On histopathological examination, biliary cystadenomas are multiloculated cysts with an epithelial lining composed of biliary-type cuboidal or non-ciliated columnar cells and, in 85%–90% of cases, are surrounded by an ovarian-like stroma [3].
The presence of ovarian stroma in mucinous liver cystadenomas suggests a correlation with ovarian mucinous cystic neoplasms. It has been suggested that the close location of the liver to the gonads during embryonic development is responsible for migration of gonadal cells into the liver and the finding of ovarian stroma in these lesions [1].
Elevated levels of CEA and CA19-9 in the cystic fluid have been typically observed in these neoplasms whereas the serum levels are inconclusive [2].
Cystadenomas are often misdiagnosed as simple cysts or hydatid cysts [3]. In case of simple cysts without internal septa or papillary projections, cystadenoma can be excluded; hydatid cysts can be differentiated on the basis of oval or round daughter cysts and coarse wall calcifications demonstrated on ultrasonography. Loculations in cystadenoma and cystadenocarcinoma are not oval or round but they appear separated by fine septations [4].
Typical features on imaging studies helpful to distinguish cystadenoma from other liver cysts include large size, internal septations and a thickened cystic wall [1]. On US, cystadenoma usually appears as an anechoic, multiseptated lesion; on Doppler US examination vascular flow can also be detected [4]. CT usually reveals a solitary cystic mass with a well-defined thick fibrous capsule, internal septa, and rarely capsular calcifications. Cystadenomas typically demonstrate rim enhancement after intravenous injection of contrast medium [3]. Polypoid, pedunculated excrescences are seen more commonly in hepatobiliary cystadenocarcinomas than in cystadenomas, although papillary areas and polypoid projections have been reported in cystadenomas without malignancy [1,5]. The diagnosis of these neoplasms is difficult preoperatively, but radiological imaging, particularly CT, plays a key role to recognise and suggest cystadenoma [5].
Complete surgical excision is considered the therapy of choice because of potential malignant degeneration into cystadenocarcinomas [1].

Differential Diagnosis List

Final Diagnosis

Mucinous hepatobiliary cystadenoma

URL:	https://www.eurorad.org/case/9127
DOI:	10.1594/EURORAD/CASE.9127
ISSN:	1563-4086