Hepatospecific MR contrast agent uptake on hepatobiliary phase can be used as a biomarker of marked β-catenin activation in hepatocellular adenoma

OBJECTIVES

To assess the value of hepatospecific MR contrast agent uptake on hepatobiliary phase (HBP) images to detect marked activation of the β-catenin pathway in hepatocellular adenomas (HCAs).

METHODS

This multicentric retrospective IRB-approved study included all patients with a pathologically proven HCA who underwent gadobenate dimeglumine-enhanced liver MRI with HBP. Tumor signal intensity on HBP was first assessed visually, and lesions were classified into three distinct groups-hypointense, isointense, or hyperintense-according to the relative signal intensity to liver. Uptake was then quantified using the lesion-to-liver contrast enhancement ratio (LLCER). Finally, the accuracy of HBP analysis in depicting marked β-catenin activation in HCA was evaluated.

RESULTS

A total of 124 HCAs were analyzed including 12 with marked β-catenin activation (HCA B+). Visual analysis classified 94/124 (76%), 12/124 (10%), and 18/124 (14%) HCAs as being hypointense, isointense, and hyperintense on HBP, respectively. Of these, 1/94 (1%), 3/12 (25%), and 8/18 (44%) were HCA B+, respectively (p < 0.001). The LLCER of HCA B+ was higher than that of HCA without marked β-catenin activation in the entire cohort (means 4.9 ± 11.8% vs. - 19.8 ± 11.4%, respectively, p < 0.001). A positive LLCER, i.e., LLCER ≥ 0%, had 75% (95% CI 43-95%) sensitivity and 97% (95% CI 92-99%) specificity, with a LR+ of 28 (95% CI 8.8-89.6) for the diagnosis of HCA B+.

CONCLUSIONS

Hepatospecific contrast uptake on hepatobiliary phase is strongly associated with marked activation of the β-catenin pathway in hepatocellular adenoma, and its use might improve hepatocellular adenoma subtyping on MRI.

KEY POINTS

• Tumor uptake on hepatobiliary phase in both the visual and quantitative analyses had a specificity higher than 90% for the detection of marked β-catenin activation in hepatocellular adenoma. • However, the sensitivity of visual analysis alone is inferior to that of LLCER quantification on HBP due to the high number of HCAs with signal hyperintensity on HBP, especially those developed on underlying liver steatosis.

Steatotic hepatocellular adenomas with different phenotypic subtypes: a case report

Hepatocellular adenomas (HCAs) are heterogeneous group of benign tumors; three pathomolecular subtypes have been identified so far: hepatocyte nuclear factor 1 α-inactivated HCA (H-HCA) (35-40%), inflammatory HCA (I-HCA) (>50%), β-catenin activated HCA (10%). Ten percent of I-HCA are also β-catenin activated. We report a rare case of three histologically confirmed steatotic HCAs of three different phenotypes: I-HCA, β-catenin activated I-HCA, and H-HCA in a 36-year-old woman. This observation outlines that in the same patient, HCA may be of different subtypes. The predisposition to develop different HCA hypothetically caused by a "benign tumorigenic field effect" may result, even rarely, in different genotypes/phenotypes such as H-HCA and I-HCA. Moreover, we illustrate the very high specificity of MR for subtyping HCA.

[An ophthalmologic diagnostic error leading to a rare systemic diagnosis: Erdheim-Chester disease]

INTRODUCTION

Erdheim-Chester disease is a rare systemic disease. The diagnosis is difficult due to significant clinical and morphological polymorphism. Orbital involvement is rare, but constitutes a classic means of detection.

OBSERVATION

We report the case of a 60-year-old man, who consulted for evaluation of bilateral retro-orbital tumors. These tumors had been discovered on head CT two years previously during work-up of proptosis. Two biopsies were performed. The first one revealed polymorphous inflammatory tissue. The second one revealed intense granulomatous reaction, rich in non-specific foamy histiocytes. Thoracic-abdominal-pelvic CT scan detected peri-aortic and retroperitoneal infiltration. The association of these signs pointed to a diagnosis of Erdheim-Chester disease, confirmed by the re-examination of the histological samples.

DISCUSSION

Erdheim-Chester disease is a rare non-Langerhans histiocytosis with a specific tropism for perivascular and fatty connective tissue. The cause is not known. The diagnosis of this systemic disease is histological.

CONCLUSION

In the case of bilateral intra-orbital tumors, the diagnosis of Erdheim-Chester disease must be considered.

Pulmonary aspergilloma in a cavity formed after percutaneous radiofrequency ablation

We report two cases of pulmonary aspergilloma (PA) in a cavity formed after percutaneous radiofrequency ablation (PRFA), a rare complication that has only been described once in the literature. The first patient was a 59-year-old white woman treated for a secondary lung nodule of an advanced hepatocellular carcinoma. One month after PRFA, a consolidation of a cavity was noticed with an "air crescent sign," and aspergilloma serology was highly positive. A bisegmentectomy was performed due to the proximity of the lesion to mediastinal vessels and the absence of significant regression after antifungal treatment. Histological examination confirmed the diagnosis of PA. The second patient was a 61-year-old white man followed-up for a non-small-cell lung cancer. A cavitation with thick margins in the ablation zone was noticed 6 months after PRFA. A biopsy was performed, and aspergilloma was diagnosed. Medical treatment with itraconazole was administered for 13 months, and there was significant regression.

Can elastometry be used for a better identification of cirrhosis?

Increased stiffness has been directly associated to fibrosis. Stage 4 fibrosis defines cirrhosis. Can elastometry (transient elastography, acoustic radiation force impulse imaging) be used for a better identification of cirrhosis? The answer is obviously yes, provided hepatologists, radiologists, pathologists, and biologists combine their expertise because severe chronic liver disease is a complex subject. Considering the pathogenesis of cirrhosis, it is likely that factors such as parenchymal extinction (leading to atrophy of the liver mass with approximation of portal tracts and hepatic veins) and exudation (congestion) play a role in liver stiffness not mentioning heart failure, liver necrosis and extrahepatic cholestasis. Neglecting these factors, elastometry will lead too often to a wrong appreciation of the degree and type of liver damage and eventually to wrong medical decision.