Intrahepatic bile duct adenoma mimicking hepatic metastasis: case report and review of the literature

Multiple bile duct adenomas mimicking hepatic metastases during laparoscopic cholecystectomy - A case report

INTRODUCTION AND IMPORTANCE

Bile duct adenoma (BDA) is a rare benign liver neoplasm, with relatively few cases reported in literature.

CASE PRESENTATION

A 55-year-old man diagnosed with symptomatic gallstone disease who underwent elective laparoscopic cholecystectomy. During the procedure, there were multiple liver nodules mimicking hepatic metastases. Histological examination and contrast-enhanced computed tomography (CECT) of the liver confirmed the diagnosis of BDA.

DISCUSSION

When incidental liver nodules are encountered intraoperatively, thorough evaluation is essential to confirm the diagnosis. Structured approach using histological examination and imaging (CECT of the liver/ MRI) confirmed the diagnosis of BDA.

CONCLUSIONS

BDA is a rare benign liver neoplasm that can be challenging to differentiate from hepatocellular carcinoma or liver metastases. Accurate identification of BDA can prevent overtreatment or mismanagement.

A Case of Resectable Single-Nodule Intrahepatic Bile Duct Adenoma

A 70-year-old man was incidentally diagnosed with a single hepatic mass lesion in his right hepatic lobe during a computed tomography scan. The lesion exhibited consistent enhancement with contrast agents on computed tomography (CT), magnetic resonance imaging (MRI), and hepatic arterial angiography. While a definitive diagnosis could not be made preoperatively, the lesion was surgically resected due to its slight enlargement over two months, suggesting a potential malignancy. Pathological examination revealed the lesion to be a bile duct adenoma (BDA). The BDA was characterized by dense proliferative small gland cavities containing several to dozens of cells. Immunohistochemical staining showed positive CK7 and negative p53. The patient remains alive and free of recurrence five years after hepatectomy. Although BDAs are rare benign hepatic tumors, they carry a risk of harboring or developing malignant tissue, such as cholangiocarcinoma. Therefore, BDAs or lesions suspicious of BDA should be surgically resected or closely monitored.

Bile duct adenoma: imaging features and radiologic-pathologic correlation

PURPOSE

This study aimed to reveal characteristic imaging features of bile duct adenoma (BDA) by radiologic-pathologic correlation.

MATERIALS AND METHODS

We retrospectively analyzed pathological and imaging findings of seven patients with BDA.

RESULTS

The median maximum diameter of BDA was 5.5 mm. Six lesions had hemispheric morphology. Seven lesions were located in the liver subcapsular region, and proliferation of bile ductules without atypia and fibrous stroma was observed. Two lesions had different microscopic findings. In both lesions, proliferation of bile ductules without atypia was observed in the margin. In one lesion, the percentage of fibrosis and hyalinization was higher at the center than at the margin. In the other lesion, inflammatory cell infiltration was observed in the center. On contrast-enhanced imaging, BDAs showed hypervascularity in the early phase and prolonged enhancement in the delayed phase. On contrast-enhanced multidetector computed tomography during hepatic arteriography, two lesions showed ring-like enhancement in the first phase and prolonged enhancement in the second phase. These were the different histopathologic features of BDAs between the margin and center.

CONCLUSION

Bile duct adenoma can be characterized as a small semicircular lesion located in the liver subcapsular region, which show hypervascularity in the early phase with prolonged enhancement.

Imaging features of bile duct adenoma: case series and review of literature

PURPOSE

We aimed to evaluate the imaging features of bile duct adenoma (BDA) on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI).

METHODS

Retrospective search in our institution database was performed for histologically confirmed BDA. Their imaging studies before histologic confirmation were reviewed. The search identified seven adults (mean age, 52.9 years) with histologically proven single BDA each. US (n=3), CT (n=5), and MRI (n=3) were performed before histologic confirmation. Additionally, a systematic English literature review for BDA and reported imaging findings since 2000 was also conducted using the following search criteria "bile duct adenoma, peribiliary hamartoma, biliary adenoma, CT, ultrasound, MRI" (date range: 01/01/2000 through 08/31/2016). The imaging findings of those cases reported were summarized and compared with our series.

RESULTS

All seven individual nodules were well circumscribed. Five lesions were located in the right hepatic lobe and two in the left hepatic lobe. On US, lesions appeared hypoechoic (n=2) and hyperechoic (n=1). BDA was hypodense on unenhanced CT images (n=1). On MRI, BDA were hypointense on T1 (n=3), hyperintense on T2 (n=3), and hyperintense on diffusion-weighted images (n=2). On contrast-enhanced CT and MRI, BDAs showed arterial phase hyperenhancement that persisted on portal venous/delayed phase images.

CONCLUSION

BDA demonstrates characteristic arterial phase hyperenhancement that persisted into the portal venous and delayed phases on CT and MRI, which may be useful in differentiating from other hepatic lesions.

Magnetic Resonance Imaging Findings of Intrahepatic Bile Duct Adenoma: A Report of 4 Cases

Intrahepatic bile duct adenoma (BDA) is a rare type of benign hepatic lesions. In this study, 4 cases of BDA diagnosed from surgical resection pathology were examined. Their clinical and magnetic resonance imaging (MRI) data were retrospectively analyzed. The 4 cases (1 men and 3 women) were aged 21 to 55 years without obvious clinical symptoms. Three were identified through routine examination. Three had a history of chronic hepatitis B virus infection. Two cases were accompanied by hepatocellular carcinoma, and one had a higher level of α-fetoprotein. The MRI images of BDA all manifested as peripheral hepatic nodules with abnormal signals. The diameters of the lesions in the 4 cases were 7.7 to 17.0 mm. The MRI images showed slight hypointensity on T1WI and slight hyperintensity on T2WI in all cases, and they showed slight hyperintensity in 2 cases and hyperintensity in 2 cases on diffusion-weighted imaging. Dynamic contrast-enhanced MRI scans show hyperintensity in the arterial phase and slight hyperintensity in the late stage in 3 cases. The other case shows hyperintensity in the arterial and portal phases and isointensity at the delayed phase. During follow-up, 3 cases were recurrence-free. The other case was complicated by the reoccurrence of HCC. In general, BDA shows specific MRI characteristics, and peripheral hepatic nodules show slight hypointensity on T1WI and slight hyperintensity on T2WI. Dynamic contrast-enhanced MRI scans showed obvious enhancement in the arterial phase and continuous enhancement at the late stage.

Contrast-enhanced ultrasonographic characteristics of an intrahepatic bile duct adenoma

Intrahepatic bile duct adenoma is a rare clinical entity which was frequently found in routine physical examinations. It is easy to be misdiagnosed due to its unspecific ultrasonographic characteristics. The major contrast-enhanced ultrasonographic characteristic of the present case was "fast in and fast out" pattern, which is difficult to be differentiated from those hypervascular hepatic tumors. The contrast-enhanced ultrasonographic characteristics need to be further studied.