Cystic tumor of the liver without ovarian-like stroma or bile duct communication: two case reports and a review of the literature

A 41-year-old Japanese woman had undergone laparoscopic deroofing due to a liver cyst in the right lobe in 2009 at another hospital. After the operation, the cystic lesion could still be confirmed by ultrasonography, and the patient subsequently underwent follow-up for blood analysis and ultrasonography every six months for three years. Recent ultrasonography revealed an increase in the size of the cystic lesion. The patient was referred to our hospital for further examination in 2012. Since the patient had a medical history of iodine hypersensitivity, we could not employ contrast-enhanced computed tomography and endoscopic retrograde cholangiography (ERC) for the examinations. Computed tomography without contrast enhancement revealed a multilocular cystic lesion, 15 cm in diameter, in the medial segment and right lobe (Figure 1A). T2-weighted magnetic resonance imaging also clearly revealed the cystic lesion (Figure 1B). Contrast-enhanced magnetic resonance imaging showed that the lesion contained multiple papillary nodular components with enhancement (Figure 1C). Diffusion-weighted magnetic resonance imaging showed diffusion restriction in the nodular components (Figure 1D). Ultrasonography with Sonazoid™ (Daiichi-Sankyo, Tokyo, Japan) revealed an enhancement corresponding to the solid component that was evident by diffusion-weighted magnetic resonance imaging. No evidence of metastases to the lymph nodes or other organs was found in the preoperative images. The extrahepatic bile duct was not dilated in the images. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, albumin, and total bilirubin levels were all within normal limits. Serology tests were negative for hepatitis B and C viruses. The serum levels of carcinoembryonic antigen and CA19-9 were within normal limits. According to the pathology report from the patient’s previous hospital, the resected cyst wall was lined by simple columnar epithelium with papillary change, no malignant changes were evident, and OS was absent in the specimen. The diagnosis in the report was cystadenoma. From the information contained in the previous report and the findings from imaging at our hospital, we could not diagnose the cystic lesion as either MCN or IPN-B, but we suspected that the solid component in the cystic lesion had a malignancy and performed right trisegmentectomy. Ten days after surgery, she developed bile leakage and underwent endoscopic retrograde nasobiliary drainage. The postoperative course was otherwise uneventful and the patient was discharged on postoperative day 64. The patient is still alive at 19 months postoperatively.

Macroscopically, the cystic lesion, 130 by 90 mm in size, was multilocular and had a solid lesion inside (Figure 2A) with a large amount of mucin. Whole liver specimens were cut into 5 to 10 mm thick pieces, which were then sliced into 5-μm sections. Histologically, the tumor showed papillary nodular growth in several cysts (Figure 2B). The tumor had complex and arborizing papillae with thin-walled vessels. The papillae or cysts were lined by multilayers of cuboidal to columnar cells with abundant eosinophilic cytoplasm forming intraepithelial lumina. The neoplastic cells had round, large, and fairly uniform nuclei with single prominent nucleoli. There was no evidence of stromal invasion; however, the tumor had sufficient cytoarchitectural atypia to be classified as having high-grade dysplasia (Figure 2C). All sections were examined carefully, but no OS were seen throughout the cyst walls (Figure 2D, E). BDC was also not evident throughout the specimens. Immunohistochemical analyses revealed that neoplastic cells were positive for MUC-5 AC and MUC-6 but not for MUC-1, MUC-2, or CDX-2. Histological and immunohistochemical findings both suggested that the tumor could be classified histologically as the oncocytic type. Since both OS and BDC were not detected in the specimen and ERC was not employed in this case, we diagnosed the cystic tumor as biliary cystadenoma, based on the WHO classification system from 2000 [1].

A 60-year-old Japanese woman came to our hospital in 2004 complaining of abdominal discomfort. Computed tomography with contrast enhancement revealed a unilocular cystic lesion, 17 cm in diameter, in the left lobe of the liver preoperatively. No nodular components were identified in the cystic lesion and no contrast enhancement was observed in the cyst wall. T2-weighted magnetic resonance imaging revealed septum-like structures in the cystic lesion (Figure 3). Ultrasonography also showed floating septum-like structures in the lesion. ERC was not scheduled. She had been afebrile before the operation. The white blood cell count and levels of C-reactive protein, carcinoembryonic antigen, and CA19-9 were within normal limits. Based on this preoperative information, the cystic lesion was diagnosed as a simple cyst or biliary cystadenoma and the attending surgeon scheduled an operation for cyst fenestration or left lobectomy. At the beginning of the operation, the surgeon punctured the cyst and found that the fluid was turbid brown. Although the total bilirubin concentration in the fluid was 2.1 mg/dl and cytological examination showed no atypical or malignant cells, the surgeon worried about the possibility of infection in the lesion and its spread to the abdominal cavity, so a left lobectomy was performed. The postoperative course was uneventful and the patient was discharged on postoperative day 16. The patient remains alive at nine years postoperatively.

Macroscopically, the cystic lesion, 200 by 150 mm in size, was unilocular, had no solid lesion inside, and did not contain mucin. Whole liver specimens were cut into 5 to 10 mm thick pieces, which were then sliced into 5-μm sections. Histologically, the cyst wall was lined by low columnar epithelia with slight cellular atypia (Figure 4). All sections were examined at the time of surgery, but no OS or BDC were seen throughout the specimens. We diagnosed the cystic tumor as biliary cystadenoma based on the WHO classification system from 2000. We carefully re-examined the whole specimens again and confirmed that there were no OS or BDC throughout the specimens.