Hepatic adenoma and focal nodular hyperplasia: a diagnostic dilemma

Subtyping of hepatocellular adenomas using Gd-EOB-DTPA: a qualitative and quantitative analysis

BACKGROUND

The goal of medical imaging is not only to identify the entity "hepatocellular adenoma," but to detect typical magnetic resonance (MR) patterns of the subtypes so that lesions with a higher malignant transformation rate could be differentiated from those that should just be controlled.

PURPOSE

To evaluate the differentiation between subtypes of hepatocellular adenomas using hepatobiliary specific contrast agent (Gd-EOB-DTPA) in MR imaging.

MATERIAL/METHODS

A total of 11 patients with 39 lesions with histologically proven hepatocellular adenomas were evaluated. Of the, 34 were inflammatory hepatocellular adenomas (IHCA) and 5 were HNF1α adenomas. No β-catenin-mutated adenoma was found. In all patients, a standard protocol considering the guidelines of the international consensus conference of Gd-EOB-DTPA was performed in a 1.5-T scanner. Besides a qualitative analysis of all sequences, we measured the quantitative signal intensity (SI) ratio in all examinations.

RESULTS

Qualitative analysis showed that best sequences for differentiation of HNF1α adenomas from IHCA were T1-weighted (T1W) precontrast (P = 0.03) and portalvenous phase (P < 0.0001) as well as arterial phase (P = 0.002). All adenomas were hypointense in hepatobiliary phase (15 min). The quantitative analyses of the SI ratio and of lesion-to-liver contrast (LLC) ratio show statistically significant differences in T1W precontrast (SI: P = 0.035; LLC: P = 0.049) and portalvenous phase (SI: P = 0.002; LLC: P = 0.002).

CONCLUSION

Subtyping of hepatocellular adenomas using Gd-EOB-DTPA is possible due to qualitative and quantitative analyses regarding T1W precontrast and portalvenous phase. In addition, the SI ratio and liver-to-lesion contrast ratio in the arterial phase gave additional qualitative information for differentiation.

Usefulness of novel imaging modalities in diagnosis of focal nodular hyperplasia of the liver

A 17-year-old woman was admitted because of a liver tumor found incidentally by ultrasonography. Liver function was normal and there were no markers of hepatitis viruses or malignancy. Abdominal ultrasonography, computed tomography (CT), and magnetic resonance imaging revealed a mass (2 cm in diameter) in the lateral segment of the left lobe of the liver. The lesion was not detected by hepatic arteriography. However, dynamic CT with fast scanning and dynamic CO2-enhanced ultrasonography demonstrated initial central enhancement of the mass followed by centrifugal spread of enhancement to the periphery. Color Doppler flow imaging detected a central color spot, shown to be an artery by a pulsed Doppler spectrum analysis. Fine-needle biopsy confirmed a diagnosis of focal nodular hyperplasia. Dynamic CT with fast scanning, dynamic CO2-enhanced ultrasonography, and color Doppler flow imaging were useful in detecting the vascular pattern specific to focal nodular hyperplasia. Investigation of further cases with these novel imaging modalities should help to establish a comprehensive diagnostic procedure and thus avoid unnecessary surgery for focal nodular hyperplasia, which is a completely benign lesion.

Liver cell adenoma in a young man with elevated serum PIVKA-II level

A 21-year-old man was referred to our hospital because of a liver mass lesion detected by abdominal ultrasonography. He had received no hormonal treatment. Physical examinations revealed no abnormalities, and laboratory data, including hepatic function test results, were within normal ranges, with the exception of elevated levels of serum protein induced by vitamin K absence or antagonist (PIVKA)-II (2.2 AU/ml). Abdominal ultrasonography revealed a hyperechoic mass lesion measuring 10 x 10 cm, with hypoechoic areas located in the right posterior segment of the liver. A low-density area and a hypervascular area were detected in the right posterior segment of the liver by computed tomography and celiac angiography, respectively. As hepatocellular carcinoma could not be completely excluded, the tumor was resected. The tissue consisted of sheets of tumor cells with eosinophilic cytoplasm and round nuclei showing a thin trabecular pattern, and these histological findings indicated liver cell adenoma. After resection of the tumor, serum PIVKA-II returned to the normal level.

Hepatic focal nodular hyperplasia: colour Doppler ultrasound can be diagnostic

Focal nodular hyperplasia (FNH) is a rare, benign, hepatic mass lesion that is usually found in young adult females. It is sometimes an incidental finding on abdominal sonography or computed tomography. Its appearance on these studies is not characteristic however, thereby creating a diagnostic problem. This report is of a case which showed a centrifugal, spokewheel pattern of pulsatile blood supply on colour Doppler US. This finding, we suggest, is sufficiently diagnostic to avoid the need for further investigation in some patients, and to direct further imaging more appropriately in others.

Dynamic MR imaging of hepatic adenomas with pathologic correlation

Two patients with hepatic adenomas (HAs) were evaluated using dynamic magnetic resonance (MR) imaging. Findings of conventional MR imaging of HAs have varied according to reports in the literature, and dynamic MR imaging of HAs has not been previously reported. Dynamic MR imaging using Gd-DTPA showed homogeneous enhancement in the early dynamic phase and prolonged enhancement in the late phase in the typical HA of Case 2. The HA of Case 1 contained fibrosis and exhibited delayed enhancement. The opacification of contrast enhancement was homogeneous and did not occur from the peripheral region as is observed in typical hemangiomas. In addition, washout of contrast material was not as rapid as with typical hepatocellular carcinomas (HCCs).