Unexpected discovery of 2 cases of hepatocyte nuclear factor 1α-mutated infracentimetric adenomatosis

Liver adenomatosis in patients with hepatocyte nuclear factor-1 alpha maturity onset diabetes of the young (HNF1A-MODY): Clinical, radiological and pathological characteristics in a French series

BACKGROUND

Liver adenomatosis (LA) is a rare disease resulting from biallelic inactivation of the hepatocyte nuclear factor-1 alpha (HNF1A) gene, which induces the proliferation of adenoma cells in liver parenchyma. Liver adenomatosis has only been documented in case reports from patients carrying a HNF1A germline mutation. We have evaluated the frequency of LA among a large cohort of patients with HNF1A-maturity onset diabetes of the young (MODY), previously termed "MODY3," and herein describe its clinical, radiological, and pathological characteristics.

METHODS

In all, 137 HNF1A-MODY subjects from 74 families were screened by liver ultrasonography in 13 centers, and 15 additional cases of LA were later included in the series. Liver adenomatosis was confirmed by liver computed tomography, magnetic resonance imaging (MRI), and/or histopathology.

RESULTS

Among 137 carriers of an HNF1A mutation, 9 patients (6.5%) from seven families were diagnosed with LA. Diabetes mellitus was present in 87.5% of patients with LA. In 25% of patients, LA was diagnosed due to intra-abdominal or intratumoral bleeding. Liver biochemistry was near normal in all patients. Liver imaging showed adenomas of various sizes and numbers. On MRI, most nodules had the radiological characteristics of steatotic adenomas. Histopathological confirmation of LA was available in 13 cases, and these adenomas were mostly steatotic. Surgery was initially performed in 37.5% of patients, and liver disease progression was observed in 30%. No disease progression was observed in 14 pregnancies.

CONCLUSIONS

The frequency of LA in a cohort of screened HNF1A-MODY patients and the high incidence of LA progression and/or hemorrhage warrants systematic screening for liver adenomatosis in HNF1A-MODY families.

Unexpected discovery of small HNF1α-inactivated hepatocellular adenoma in pathological specimens from patients resected for liver tumours

BACKGROUND AND AIMS

It is rare but not uncommon to discover micro/small HNF1α-inactivated hepatocellular adenoma (H-HCA) outside the context of resected H-HCA. We aimed to review our cases of micro/small H-HCA discovered by chance on different kinds of liver resected specimens.

METHODS

We retrieved cases of micro/small H-HCA discovered by chance on resected specimens outside the context of H-HCA. All these nodules were liver fatty acid binding protein (LFABP)-negative contrasting with normal positivity in the surrounding non-tumoural liver, ruling out the possibility of focal steatosis or other subtypes of micro-HCAs.

RESULTS

We identified 19 micro/small H-HCA cases. In 16 cases they were discovered in patients who underwent surgery for benign nodules including one haemangioma, six focal nodular hyperplasia, seven inflammatory HCA (including one with b-catenin activation), one HCA, whose subtype could not be identified because of massive necrosis/hemorrhage, and one hepatocellular carcinoma. In two additional cases, patients followed up for a melanoma underwent liver surgery to remove micro nodules possibly related to a metastatic process. Finally in one case a micro nodule was seen and resected during a cholecystectomy.

CONCLUSION

Taken together, H-HCAs are more frequent than we initially supposed as micro and small HCAs cannot all be detected by routine ultrasound. Despite no information on the potential growth of these micro/small H-HCAs, there is no argument to stop oral contraceptives or to ask for a specific regular surveillance. The association of different subtypes of HCAs with focal nodular hyperplasia suggests they share or have common etiological factors.

Hepatocellular benign tumors-from molecular classification to personalized clinical care

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are benign hepatocellular tumors that develop most frequently in women without cirrhosis. Genomic approaches have identified signaling pathways related to these benign hepatocyte proliferations. FNH, a polyclonal lesion, is characterized by local vascular abnormalities and heterogeneous activation of Wnt/β-catenin and transforming growth factor β signaling. Four major subgroups of HCAs have been identified based on mutations in specific oncogenes and tumor suppressor genes. Each molecular subtype of HCA has been associated with specific pathways, providing new information about benign tumorigenesis. Key features include metabolic alterations (induced by defects in HNF1A), oncogene-induced inflammation (activation of JAK-STAT signaling in inflammatory adenomas), and an association between activation of Wnt/β-catenin signaling and progression of HCAs in hepatocellular carcinomas. Benign hepatocellular tumors can be classified using immunohistochemical analyses. Studies of genotypes and phenotypes of FNH and HCAs have led to the identification of risk factors and improved invasive and noninvasive diagnostic techniques, evaluation of prognosis, and treatment. We review the molecular pathways involved in benign hepatocyte proliferation and discuss how this basic knowledge has been progressively translated into personalized clinical care.

Hepatic resection for inflammatory hepatocellular adenomas: pathological identification of micronodules expressing inflammatory proteins

BACKGROUND

Inflammatory hepatocellular adenoma (IHCA) defines a subgroup of hepatocellular adenomas characterized by the expression of members of the acute-phase inflammatory response [(serum amyloid A protein (SAA) and C-reactive protein (CRP)]. IHCA are unique or multiple as defined by the presence of several nodule(s) larger than 10 mm using both imaging and macroscopic observation. Frequently, additional micronodules (<10 mm), previously undetected by imaging, can be observed in resected specimens.

AIMS

To analyse micronodules in multiple (group 1, nine patients) and single (group 2, eight patients) IHCA cases, immunohistochemistry using SAA and CRP antibodies was performed on all nodules detected under macroscopic examination as well as on surrounding tissue with no visible nodules.

RESULTS

Nodules of different sizes (>5 < or = 10 mm, > or = 1 < or = 5 mm) were found in group 1, whereas only rare nodules in the mm range were found in group 2. Micronodules shared the characteristics of large nodules, which justified surgery such as inflammatory infiltrates, abnormal arteries, sinusoidal dilatation or peliosis. However, the number of these characteristics was proportional to the size of the nodules.

CONCLUSION

This study demonstrates that the real number of IHCA is greater than that predicted from imaging-based analyses. In addition, we show that patients with more than one nodule present a greater chance to display more and larger undetected micronodules than patients with a single nodule.