Molecular pathogenesis of focal nodular hyperplasia and hepatocellular adenoma

Benign hepatocellular nodules of healthy liver: focal nodular hyperplasia and hepatocellular adenoma

Owing to the progress of imaging techniques, benign hepatocellular nodules are increasingly discovered in the clinical practice. This group of lesions mostly arises in the context of a putatively normal healthy liver and includes either pseudotumoral and tumoral nodules. Focal nodular hyperplasia and hepatocellular adenoma are prototypical examples of these two categories of nodules. In this review we aim to report the main pathological criteria of differential diagnosis between focal nodular hyperplasia and hepatocellular adenoma, which mainly rests upon morphological and phenotypical features. We also emphasize that for a correct diagnosis the clinical context such as sex, age, assumption of oral contraceptives, associated metabolic or vascular disturbances is of paramount importance. While focal nodular hyperplasia is a single entity epidemiologically more frequent than adenoma, the latter is representative of a more heterogeneous group which has been recently and extensively characterized from a clinical, morphological, phenotypical and molecular profile. The use of the liver biopsy in addition to imaging and the clinical context are important diagnostic tools of these lesions. In this review we will survey their systematic pathobiology and propose a diagnostic algorithm helpful to increase the diagnostic accuracy of not dedicated liver pathologists. The differential diagnosis between so-called typical and atypical adenoma and well differentiated hepatocellular carcinoma will also be discussed.

Cyp1b1 affects external control of mouse hepatocytes, fatty acid homeostasis and signaling involving HNF4α and PPARα

Cytochrome P450 1b1 (Cyp1b1) is expressed in endothelia, stellate cells and pre-adipocytes, but not hepatocytes. Deletion alters liver fatty acid metabolism and prevents obesity and hepatic steatosis. This suggests a novel extra-hepatocyte regulation directed from cells that express Cyp1b1. To characterize these mechanisms, microarray gene expression was analyzed in livers of normal and congenic Cyp1b1-ko C57BL/6 J mice fed either low or high fat diets. Cyp1b1-ko gene responses indicate suppression of endogenous PPARα activity, a switch from triglyceride storage to mitochondrial fatty acid oxidation and decreased oxidative stress. Many gene responses in Cyp1b1-ko are sexually dimorphic and correspond to increased activity of growth hormone mediated by HNF4α. Male responses stimulated by GH pulses are enhanced, whereas responses that decline exhibit further suppression, including Cyp regulation by PPARα, CAR and PXR. These effects of Cyp1b1 deletion overlap with effects caused by deletion of the small heterodimeric partner, a suppressor of these nuclear factors. Redirection of gene expression associated with liver fat homeostasis in Cyp1b1-ko mice that directs hypothalamic control of GH and leptin. Cyp1b1-ko suppresses neonatal Scd1 and delays adult maturation of dimorphic GH/HNF4α signaling. Alternatively, deletion may diminish hypothalamic metabolism of estradiol, which establishes adult GH regulation.

Hepatocellular adenoma classification: a comparative evaluation of immunohistochemistry and targeted mutational analysis

BACKGROUND

Four subtypes of hepatocellular adenomas (HCA) are recognized: hepatocyte-nuclear-factor-1α mutated (H-HCA), β-catenin-mutated type with upregulation of glutamine synthetase (b-HCA), inflammatory type (IHCA) with serum-amyloid-A overexpression, and unclassified type. Subtyping may be useful since b-HCA appear to have higher risk of malignant transformation. We sought to apply subtype analysis and assess histological atypia, correlating these with next-generation sequencing analysis.

METHODS

Twenty-six HCA were stained with serum amyloid A (SAA), liver fatty acid-binding protein (LFABP), glutamine synthetase (GS), and β-catenin IHC, followed by analysis with a targeted multiplex sequencing panel.

RESULTS

By IHC, 4 HCA (15.4 %) were classified as b-HCA, 11 (42.3 %) as IHCA, 9 (34.6 %) as H-HCA, and two (7.7 %) unclassifiable. Eight HCA (30.8 %) showed atypia (3 b-HCA, 4 IHCA and 1 H-HCA). Targeted sequencing confirmed HNF1A mutations in all H-HCA, confirming reliability of LFABP IHC in identifying these lesions. CTNNB1 mutations were detected in 1 of 4 (25 %) of GS/β-catenin-positive cases, suggesting that positive GS stain does not always correlate with CTNNB1 mutations.

CONCLUSIONS

Immunohistochemistry does not consistently identify b-HCA. Mutational analysis improves the diagnostic accuracy of β-catenin-mutated HCA and is an important tool to assess risk of malignancy in HCA.

Ultrasound features of hepatocellular adenoma and the additional value of contrast-enhanced ultrasound

BACKGROUND

Hepatocellular adenoma (HCA) is a rare benign tumor of the liver. It is of clinical importance to differentiate HCA from other liver tumors, especially hepatocellular carcinoma (HCC). This study aimed to evaluate the characteristic features of HCA by conventional ultrasound and contrast-enhanced ultrasound (CEUS) findings.

METHODS

Twenty-six patients (10 males and 16 females; mean age 36.2+/-5.0 years) with 26 histopathologically proven HCAs were retrospectively identified. According to the maximum diameter of HCAs, they were divided into three groups: <30 mm, 30-50 mm, and >50 mm. Ultrasound examinations were performed with C5-2 broadband curved transducer of Philips iU22 unit (Philips Bothell, WA, USA). For each lesion, a dose of 2.4 mL SonoVue® (Bracco Imaging Spa, Milan, Italy) was injected as a quick bolus into the cubital vein. Lesions' echogenicity, color-Doppler flow imaging and contrast enhancement patterns were recorded.

RESULTS

Grayscale ultrasound revealed that most of HCAs were hypoechoic (73.1%, 19/26). Spotty calcifications were detected in 26.9% (7/26) of the lesions. Color-Doppler flow imaging detected centripetal bulky color flow in 46.2% (12/26) of the HCAs. CEUS showed that 73.1% (19/26) of the HCAs displayed as rapid, complete and homogenous enhancement, and 53.8% (14/26) showed decreased contrast enhancement in the late phase. There was no significant difference in enhancement patterns among different sizes of HCAs (P>0.05). Centripetal enhancement with subcapsular tortuous arteries was common in larger HCAs.

CONCLUSIONS

CEUS combined with grayscale and color-Doppler flow imaging helped to improve preoperative diagnosis of HCAs. The characteristic imaging features of HCAs included: rapid homogeneous enhancement and slow wash-out pattern on CEUS; heterogeneous echogenicity on grayscale ultrasound; and centripetal enhancement with subcapsular tortuous arteries in large HCAs.

Variable uptake feature of focal nodular hyperplasia in Tc-99m phytate hepatic scintigraphy/single-photon emission computed tomography-A parametric analysis

Tc-99m phytate hepatic scintigraphy remains the standard method for evaluating the functional features of Kupffer cells. In this study, we demonstrate the variable uptake feature of focal nodular hyperplasia (FNH) in Tc-99m phytate scintigraphy. We reviewed all patients who underwent Tc-99m phytate hepatic scintigraphy between 2008 and 2012 in Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. Cases with FNH were diagnosed on the basis of pathology or at least one or more prior imaging with a periodic clinical follow-up. All patients received a standard protocol of dynamic flow study and planar and Tc-99m phytate single-photon emission computed tomography (E. CAM; Siemens). The correlation of variable nodular radioactivity with parameters such as tumor size and localization was analyzed. In total, 15 lesions of 14 patients in the clinic were diagnosed as FNH. The tumor size was approximately 2.9-7.4 cm (mean size 4.6 cm). Four lesions were larger than 5 cm. The major anatomic distribution was in the right hepatic lobe (10 lesions), particularly in the superior segments (7 lesions). Tc-99m phytate single-photon emission computed tomography imaging for determining the functional features of Kupffer cells included cool/cold (8 lesions), isoradioactive/warm (6 lesions), and hot (1 lesion) patterns of uptake. We did not observe any statistically significant correlation between variable nodular radioactivity and tumor size (p=0.68) or localization (p=0.04). Herein, we demonstrate the variable uptake feature of FNH in Tc-99m phytate scintigraphy. In small FNH tumors (< 5 cm), increased or equal uptake still provided specificity for the differential diagnosis of hepatic solid tumors.

Pigmented hepatocellular adenomas have a high risk of atypia and malignancy

Pigment deposition is occasionally seen in hepatocellular adenomas. Several reports suggest that pigmented hepatocellular adenomas have increased risk of malignancy, but these tumors remain incompletely understood. To determine the frequency of pigment deposition, we evaluated and classified 109 well-differentiated hepatocellular neoplasms that were originally diagnosed or submitted in consultation as hepatocellular adenomas and found 27 (25%) pigmented tumors. All were negative on iron stain and in three cases electron microscopy confirmed the pigment was lipofuscin. The lipofuscin intensely stained with glypican-3 in most cases (89%). Of the 27 pigmented tumors, 11 cases (41%) were classified as hepatocellular adenomas, 7 cases (27%) were classified as atypical hepatocellular adenomas/hepatocellular neoplasms of uncertain malignant potential, and 9 cases (33%) were reclassified as well-differentiated hepatocellular carcinomas. Four (of 9) hepatocellular carcinomas arose in pigmented hepatocellular adenomas, giving a rate of malignant transformation in pigmented hepatocellular adenomas of 27%. Of the total 27 pigmented tumors, 78% were in women and 22% in men, but interestingly only men had tumors classified as hepatocellular carcinoma or hepatocellular neoplasm of uncertain malignant potential. Also of note, a total of 10 individuals (37%) had multiple hepatocellular neoplasms but in 9 of these cases the other adenomas were non-pigmented. Importantly, in cases with multiple hepatocellular neoplasms, only the pigmented hepatocellular neoplasms had atypia or malignancy. Genotype-phenotype classification of the pigmented tumors showed different subtypes: HNF1α inactivated (48%), β-catenin activated (26%), inflammatory (15%), concurrently β-catenin activated and inflammatory in 1 hepatocellular adenoma, concurrently HNF-1α inactivated and β-catenin activated in 1 hepatocellular adenoma, and unclassified in 1 hepatocellular carcinoma. In conclusion, hepatocellular adenomas with lipofuscin pigment are a heterogeneous group of adenomas, with HNF-1α inactivation being the commonest genotype. They have an increased risk of atypia and malignancy, especially in males.

Benign liver tumors in pediatric patients - Review with emphasis on imaging features

Benign hepatic tumors are commonly observed in adults, but rarely reported in children. The reasons for this remain speculative and the exact data concerning the incidence of these lesions are lacking. Benign hepatic tumors represent a diverse group of epithelial and mesenchymal tumors. In pediatric patients, most benign focal liver lesions are inborn and may grow like the rest of the body. Knowledge of pediatric liver diseases and their imaging appearances is essential in order to make an appropriate differential diagnosis. Selection of the appropriate imaging test is challenging, since it depends on a number of age-related factors. This paper will discuss the most frequently encountered benign liver tumors in children (infantile hepatic hemangioendothelioma, mesenchymal hamartoma, focal nodular hyperplasia, nodular regenerative hyperplasia, and hepatocellular adenoma), as well as a comparison to the current knowledge regarding such tumors in adult patients. The current emphasis is on imaging features, which are helpful not only for the initial diagnosis, but also for pre- and post-treatment evaluation and follow-up. In addition, future perspectives of contrast-enhanced ultrasound (CEUS) in pediatric patients are highlighted, with descriptions of enhancement patterns for each lesion being discussed. The role of advanced imaging tests such as CEUS and magnetic resonance imaging, which allow for non-invasive assessment of liver tumors, is of utmost importance in pediatric patients, especially when repeated imaging tests are needed and radiation exposure should be avoided.

Benign solid tumors of the liver: management in the modern era

BACKGROUND

Recently, there has been a growing interest in solid benign liver tumors as the understanding of the pathogenesis and molecular underpinning of these lesions continues to evolve. We herein provide an evidence-based review of benign solid liver tumors with particular emphasis on the diagnosis and management of such tumors.

METHODS

A search of all available literature on benign hepatic tumors through a search of the MEDLINE/PubMed electronic database was conducted.

RESULTS

New diagnostic and management protocols for benign liver tumors have emerged, as well as new insights into the molecular pathogenesis. In turn, these data have spawned a number of new studies seeking to correlate molecular, clinicopathological, and clinical outcomes for benign liver tumors. In addition, significant advances in surgical techniques and perioperative care have reduced the morbidity and mortality of liver surgery. Despite current data that supports conservative management for many patients with benign liver tumors, patients with severe preoperative symptomatic disease seem to benefit substantially from surgical treatment based on quality of life data.

CONCLUSION

Future studies should seek to further advance our understanding of the underlying pathogenesis and natural history of benign liver tumors in order to provide clinicians with evidence-based guidelines to optimize treatment of patients with these lesions.

MR characterization of focal liver lesions: pearls and pitfalls

Magnetic resonance (MR) can characterize specific tissue subtypes, thus facilitating focal liver lesion diagnosis. Focal liver lesions that are isointense to hyperintense to liver on T1-weighted images are usually hepatocellular in origin. Chemical shift imaging can narrow the differential diagnosis by detecting the presence of lipid or iron. T2 and heavily T2-weigthed fast spin echo imaging can differentiate solid from nonsolid focal liver lesions. The authors illustrate these MR imaging pearls and the uncommon exceptions (pitfalls). The authors hope that you will find this less traditional contribution to the Magnetic Resonance Clinics of North America helpful in clinical practice.

Current updates on the molecular genetics and magnetic resonance imaging of focal nodular hyperplasia and hepatocellular adenoma

Focal nodular hyperplasia (FNH) and hepatocellular adenomas (HCAs) constitute benign hepatic neoplasms in adults. HCAs are monoclonal neoplasms characterised by an increased predilection to haemorrhage and also malignant transformation. On the other hand, FNH is a polyclonal tumour-like lesion that occurs in response to increased perfusion and has an uneventful clinical course. Recent advances in molecular genetics and genotype-phenotype correlation in these hepatocellular neoplasms have enabled a new classification system. FNHs are classified into the typical and atypical types based on histomorphological and imaging features. HCAs have been categorised into four subtypes: (1) HCAs with HNF-1α mutations are diffusely steatotic, do not undergo malignant transformation, and are associated with familial diabetes or adenomatosis. (2) Inflammatory HCAs are hypervascular with marked peliosis and a tendency to bleed. They are associated with obesity, alcohol and hepatic steatosis. (3) HCAs with β-catenin mutations are associated with male hormone administration and glycogen storage disease, frequently undergo malignant transformation and may simulate hepatocellular carcinoma on imaging. (4) The final type is unclassified HCAs. Each of these except the unclassified subtype has a few distinct imaging features, often enabling reasonably accurate diagnosis. Biopsy with immunohistochemical analysis is helpful in difficult cases and has strong implications for patient management.

TEACHING POINTS

• FNHs are benign polyclonal neoplasms with no risk of haemorrhage or malignancy. • HCAs are benign monoclonal neoplasms classified into four subtypes based on immunohistochemistry. • Inflammatory HCAs show an atoll sign with a risk of bleeding and malignant transformation. • HNF-1α HCAs are steatotic HCAs with minimal complications and the best prognosis. • β-Catenin HCA shows variable MRI features and a high risk of malignancy.

Development of multifocal nodular lesions of a liver mimicking hepatic metastasis, following resection of an insulinoma in a child

Insulinoma, which arises from insulin-producing pancreatic beta cells, is a rare tumor in children. Only 5%-10% of insulinomas are malignant and undergo metastasis. We report a case of an 11-year-old girl who experienced hypoglycemia-related seizures induced by an insulinoma; after resection of the primary tumor, she developed hepatic focal nodular hyperplasia (FNH). Laboratory test results indicated marked hypoglycemia with hyperinsulinemia. Abdominal ultrasonography (US) and computed tomography results were normal; however, magnetic resonance imaging (MRI) showed a solid mass in the pancreatic tail. Therefore, laparoscopic distal pancreatectomy was performed. Two months after the surgery, an abdominal MRI revealed multiple nodular lesions in the liver. An US-guided liver biopsy was then performed, and histological examination revealed FNH without necrosis or mitotic activity. The patient has been free of hypoglycemia for 2 years, and recent MRI studies showed a decrease in the size of FNH lesions, without any evidence of metastasis. Even though no metastatic lesions are noted on imaging, close observation and follow-up imaging studies are required in a child with insulinoma that has malignant potential on histopathologic findings.

National trends in the use of surgery for benign hepatic tumors in the United States

BACKGROUND

The widespread use of diagnostic imaging has led to an increase in the incidence and diagnosis of benign liver tumors. The objective of this study was to define the overall use and temporal trends of operative procedures for benign liver tumors using a nationally representative cohort.

METHODS

All patients who underwent liver surgery for benign liver tumors between 2000 and 2011 were identified from the Nationwide Inpatient Sample database. Trends in annual volume of liver procedures were analyzed using the average annual percent change (AAPC) assessed by joinpoint analysis.

RESULTS

There were 2,489 open (94.5%) and 144 (5.5%) minimally invasive surgical (MIS) procedures. Partial hepatectomy accounted for 43.8% of all cases (n = 1,153). Surgery for patients with benign liver tumors increased from 156 in 2000 to 272 in 2011 (AAPC, 5.8%; 95% CI, 3.2-8.6%). There was decline in the relative use of open operative procedures from 98.1% in 2000 to 92.3% in 2011 (AAPC, -0.4%; 95% CI, -0.7 to -0.1%). In contrast, the proportion of MIS procedures increased from 1.9% in 2000 to 7.7% in 2011 (AAPC, 7.4%; 95% CI, 1.9-13.3%). The median duration of stay among all patients was 5 days (interquartile range, 4-7; 5 days [open] vs 3 days [MIS]; P < .001). Inpatient mortality was 0.6% (n = 15 [open] vs n = 0 [MIS]; P = .43) and did not change during the study period (P > .05).

CONCLUSION

Overall volume of surgical management of benign liver tumors has increased substantially over the past decade. There has been a relative shift away from open procedures toward MIS procedures.

Focal nodular hyperplasia of the liver: an emerging complication of hematopoietic SCT in children

Hepatic focal nodular hyperplasia (FNH) is a nonmalignant condition rarely affecting children previously treated for cancer, especially those who received hematopoietic SCT (HSCT). Some aspects of its pathogenesis still remain unclear and a strong association with specific risk factors has not yet been identified. We report here a single institution's case series of 17 patients who underwent HSCT and were diagnosed with FNH, analyzing retrospectively their clinical features and the radiological appearance of their hepatic lesions. We aimed to compare the diagnostic accuracy of ultrasound (US) and magnetic resonance imaging (MRI) and to explore the role of transient elastography (FibroScan) to evaluate the degree of hepatic fibrosis in FNH patients. Our analysis showed an association of FNH with age at transplant ⩽12 years (hazard ratio (HR) 9.10); chronic GVHD (HR 2.99); hormone-replacement therapy (HR 4.02) and abdominal radiotherapy (HR 4.37). MRI proved to be a more accurate diagnostic tool compared with US. Nine out of 12 patients who underwent FibroScan showed hepatic fibrosis. Our study points out that FNH is an emerging complication of HSCT, which requires a lifelong surveillance to follow its course in cancer patients.

Global transcriptome analysis of peripheral blood identifies the most significantly down-regulated genes associated with metabolism regulation in Klinefelter syndrome

The molecular pathogenesis of Klinefelter Syndrome (KS) is not fully understood. The aim of this study was to determine differences in gene expression patterns between KS patients and control individuals to help identify disease-related genes and biological pathways. Gene expression profiles of five KS patients and five healthy men were determined by microarray; 21 differentially expressed genes with a fold-change >1.5 and q-value <0.05 were identified between the groups. Genes associated with metabolism regulation and encoding liver fatty acid-binding protein (FABP1), aldehyde dehydrogenase 1 family member L1 (ALDH1L1), and vitronectin (VTN) were the most-significantly down-regulated in KS, as confirmed by quantitative reverse transcription PCR. Notably, none of these differentially expressed genes are normally found on the X chromosome. Thus, our results indicate that aberrant metabolism is involved in the pathogenesis of KS. Further elucidation of the how aberrant expression of metabolism-related genes affect the pathogenesis of KS may lead to the development of novel preventative and therapeutic strategies.

Diagnosis and management of solid benign liver lesions

More and more asymptomatic benign liver tumours are discovered incidentally and can be divided into regenerative lesions and true neoplastic lesions. The most common regenerative lesions include hemangioma, focal nodular hyperplasia and inflammatory pseudotumours of the liver. Neoplastic lesions include hepatocellular adenomas and angiomyolipomas. Regenerative lesions rarely increase in volume, do not yield a higher risk of complications and usually do not require treatment. By contrast, hepatocellular adenomas and angiomyolipomas can increase in volume and are associated with a risk of complications. Large hepatocellular adenomas (>5 cm in diameter) are undoubtedly associated with a risk of bleeding and malignant transformation, particularly the inflammatory (also known as telangiectatic) and β-catenin mutated subtypes. Accurate diagnosis needs to be obtained to select patients eligible for surgical resection. MRI has markedly improved diagnosis and can identify the major hepatocellular adenomas subtypes. The use of biopsy results to inform the indication for resection remains questionable. However, when diagnosis remains uncertain after imaging, percutaneous biopsy could help improve diagnostic accuracy.

Imaging of benign hepatocellular lesions: current concepts and recent updates

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are a variety of solid lesions mostly found in the absence of underlying chronic liver disease in young patients. HCA is no longer to be considered as a unique lesion but as a recollection of different entities sharing common points but most of all separated by different typical morphological aspects. Accurate diagnosis is of clinical importance as the management is most of the time conservative for FNH, whereas HCAs expose patients to hemorrhage and malignant transformation, and may lead to a more invasive treatment, mainly surgical resection. Moreover, the different HCA subtypes expose to different risks of complication. The best imaging techniques for the differentiation between FNH and HCAs and for the subtyping of HCAs are contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging (MRI), as specific combinations of imaging features have been associated with the different lesions. They should be considered as complementary examinations. Atypical or multiple lesions, lesions containing fat or presence of an associated steatosis represent diagnostic challenges. Recently, MR hepatospecific contrast agents have been shown to be useful. Emergent elastography techniques might also be helpful in the near future. Biopsy should always be performed in case of uncertain diagnosis to reach a final diagnosis and avoid unnecessary invasive treatment.

Polycystic ovary syndrome as a rare association with inflammatory hepatocellular adenoma: a case report

Hormonal factors, like oral contraceptives, create a predisposition to hepatocellular adenoma. We present the case of a young woman with an inflammatory hepatocellular adenoma occurring in the context of a polycystic ovary syndrome. In view of this possible relationship, it would be recommended to follow up patients with hyperandrogenism with repeated liver tests and ultrasonographics. Furthermore, this observation illustrated some difficulties to differentiate remodelled inflammatory hepatocellular adenoma and focal nodular hyperplasia and underlined the interest of immunohistochemical markers for the right diagnosis.

Gene mutations in hepatocellular adenomas

Hepatocellular adenomas (HCA) are rare, benign liver tumours that often occur in women of reproductive age. HCA has been associated with the use of oral contraceptives, but the increased incidence of the tumour in older women and in men has linked the tumour type to other diseases, including the metabolic syndrome. Genotypical classification of the adenomas has led to the identification of four subgroups that correlate genotype with phenotype: human hepatocyte nuclear factor-1 alpha (HNF1α) inactivating HCA, β-catenin activating HCA, inflammatory HCA and unclassified HCA. HNF1α inactivating HCA is associated with bi-allelic mutations in the TCF1 gene and morphologically has marked steatosis. β-catenin activating HCA has increased activity of the Wnt/β-catenin pathway and is associated with possible malignant transformation. Inflammatory HCA is characterized by an oncogene-induced inflammation due to alterations in the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. In the diagnostic setting, sub classification of HCA is based primarily on immunohistochemical analyzes, and has had an increasing impact on choice of treatment and individual prognostic assessment. This review offers an overview of the reported gene mutations associated with hepatocellular adenomas together with a discussion of the diagnostic and prognostic value.

Hyperplastic hepatocellular nodule with localized hemangiomatosis: A hither-to unrecognized type of hypervascular hepatic lesion

AIM

The differential diagnosis of hypervascular hepatocellular nodular lesion includes hepatocellular carcinoma and it is sometimes difficult to image. We report herein two patients with hyperplastic hepatocellular nodule associated with localized hemangiomatosis.

METHODS

A hypervascular hepatic nodule approximately 10 mm in diameter was incidentally detected in a 79-year-old woman and a 58-year-old man. Hepatocellular carcinoma was suspected and partial hepatectomy was performed.

RESULTS

Hepatitis viral markers and tumor markers were negative in both patients. On histology, the nodular lesions had an ill-defined border and included hemangioma-like vessels and sinusoidal dilatation showing immunoreactivity for CD34. There were no abnormal unpaired arteries or a central stellate scar suggesting focal nodular hyperplasia. Hepatic columns in the lesion were thickened to two to three cell layers and cellular density was mildly more increased than the background liver. Cellular atypia and diminished reticulin fibers around the hepatic column were not observed. A survey of the background livers of 13 patients with cavernous hemangioma disclosed similar hemangioma-like vessels in hepatic parenchyma in six patients (46%), but similar nodular lesions were not detected in any patients.

CONCLUSION

Taken together, the hepatic lesions in these two patients may be hither-to unrecognized types of hyperplastic hepatocellular lesion associated with localized hemangiomatous lesion that may cause irregular blood flow.

Update on the new classification of hepatic adenomas: clinical, molecular, and pathologic characteristics

CONTEXT

Hepatic adenoma is an uncommon, benign, hepatic neoplasm that typically occurs in women of child-bearing age, often with a history of long-term use of oral contraceptive drugs. This is usually detected as an incidental mass lesion in a noncirrhotic liver during imaging studies. Pathologic evaluation by needle core biopsy remains the gold standard for diagnosis. Molecular studies have revealed that hepatic adenomas involve unique molecular pathways that are distinct from hepatocellular carcinoma. Based on these studies, a French collaborative group has recently proposed a molecular-pathologic classification for hepatic adenomas. In addition, advances in molecular studies have led to reclassification of the "telangiectatic variant of focal nodular hyperplasia" as "hepatic adenoma, inflammatory subtype."

OBJECTIVE

To review the proposed, new classification of hepatic adenoma and the changes in diagnostic workup in light of the above-mentioned developments.

DATA SOURCES

Review of published literature and illustrations from clinical case material.

CONCLUSIONS

Definitive diagnosis of liver mass lesion on needle core biopsies has a decisive role in clinical management. With the advent of the new classification of hepatic adenomas and its prognostic implications, it is vital for pathologists to be aware of the morphologic features seen in different subtypes and the available diagnostic tools, such as immunohistochemistry, to help identify the correct subtype.

Liver adenomatosis: serial investigation on MRI

PURPOSE

To describe the natural history of liver adenomatosis (LA), including complications and changes in lesion size over time.

MATERIALS AND METHODS

Eighteen patients with clinical diagnosis of LA were included. Clinical and biochemical information were collected. The initial and follow-up MR studies were reviewed retrospectively to determine change in lesion size and imaging features.

RESULTS

Seventeen patients were women (94.4%). The mean age of the initial MR study was 37.0 years (18-52 years). The median size of the largest lesion was 6.7 cm (range 3.0-13.5 cm). Intratumoral bleeding was detected on MRI in 9 lesions, in 7 patients (38.8%). The median size for hemorrhagic lesions was 7.6 cm (range 4.1-13.5 cm). During the mean follow-up period of 29.4 (range 4-98) months, 10 patients had stable disease (55.6%), and 8 patients had tumor regression (44.4%). Of 8 patients who were followed without intervention, 3 patients (37.5%) had spontaneous regression. No malignant transformation or lesion progression was occurred.

CONCLUSION

During an over 2-year follow-up period, the majority of lesions of LA appeared to remain stable or showed tumor regression. Spontaneous tumor regression can be observed in approximately 37% of individuals in the age range of 28-53 years.

Inflammatory hepatocellular adenomas can mimic focal nodular hyperplasia on gadoxetic acid-enhanced MRI

OBJECTIVE

Inflammatory hepatocellular adenoma (HCA) is a recently categorized entity of hepatocellular neoplasms. We investigated whether gadoxetic acid-enhanced MRI can distinguish inflammatory HCA from focal nodular hyperplasia (FNH).

MATERIALS AND METHODS

From January 1, 2009, through January 1, 2013, gadoxetic acid-enhanced MRI examinations from two institutions were reviewed for HCA, with specific histologic features of inflammatory HCA. Biopsy and resection slides were reviewed, and immunohistochemistry for glutamine synthetase was performed in a subset to confirm the initial diagnosis.

RESULTS

A total of 10 possible cases of inflammatory HCA were identified in the pathology database. On the basis of glutamine synthetase staining performed for this study, three cases were rediagnosed as FNH and thus were excluded from the study. Therefore, a total of seven patients with inflammatory HCA were identified. On gadoxetic acid-enhanced MRI, four of these patients had classic features of FNH (group A, FNH mimics), and three had imaging features suggestive of HCA (group B, typical inflammatory HCA). Imaging features that were considered diagnostic of FNH included isointense or minimal T2 hyperintensity, arterial enhancement, and diffuse hyperintensity on hepatobiliary phase. Three of the four patients with FNH mimics had slides available for pathologic rereview, and the diagnosis of inflammatory HCA was supported by glutamine synthetase immunohistochemistry findings. The pathology reports of the remaining four cases were rereviewed and were also found to have features consistent with inflammatory HCA.

CONCLUSION

Inflammatory HCA can mimic FNH on MRI, including hepatobiliary phase hyperintensity. Moreover, conventional pathology using histopathology alone may lead to misclassification of inflammatory HCA.

A case of progressing focal nodular hyperplasia and its molecular expression pattern

We report the case of an adult male with progressing focal nodular hyperplasia (FNH). Although imaging studies suggested that the tumor was a classical FNH, the tumor biopsy showed glutamine synthetase expression and heat shock protein 70 in part of the tumor. As we could not definitely distinguish this case of FNH from early hepatocellular carcinoma (HCC), we performed laparoscopic partial hepatectomy. The surgical resected specimen showed that the tumor had a central scar with vascular and cholangiolar proliferation, which is compatible with FNH. Immunohistochemical analysis showed that the molecular expression pattern was compatible with FNH in the center of the tumor, whereas it partly resembled early HCC in the periphery of the tumor. FNH progression is occasionally found, and the molecular pattern of the progressing area in FNH might resemble that of early HCC due to morphologic and phenotypic changes induced by the regenerative mechanism and the alteration of blood flow. We should carefully observe progressing FNH.

Multifocal hepatic neoplasia in 3 children with APC gene mutation

Hepatoblastoma (HB), the most common hepatic neoplasm in children is associated with germline mutations in adenomatous polyposis coli tumor-suppressor gene that cause familial adenomatous polyposis syndrome. Individuals with familial adenomatous polyposis have a 750 to 7500× the risk of developing HB. We report 3 children with APC gene mutation, who underwent resection or liver transplant for HB. In addition to HB, all 3 patients had multiple independent adenoma-like nodules lacking qualities of intrahepatic metastases. Twenty-five nodules were subjected to immunohistochemical analysis using a panel of antibodies including glypican-3 (GPC3), β-catenin, cytokeratin AE1/AE3, CD34, Ki-67, glutamine synthetase (GS), and fatty acid binding protein. The nodules were round, ranged in size from 0.2 to 1.5 cm, and paler than the background liver. All lacked the chemotherapy effect. The nodules were circumscribed but nonencapsulated and composed of well-differentiated hepatocytes with occasional minor atypical features and absent or rare portal tracts. One lesion displayed a "nodule-within-nodule" pattern. The nodules demonstrated diffuse GS overexpression. Nine (36%) nodules were focally reactive for GPC3, and 1 (4%) displayed focal nuclear β-catenin expression. The associated HB showed diffuse expression of GS, GPC3, and β-catenin nuclear staining. We interpret these nodules as neoplastic with most being adenomas (GPC3 negative) that show features of independent origin and represent early stages of carcinogenesis, implying potential to progress to HB or hepatocellular carcinoma. To our knowledge, this is the first report of multifocal neoplasms in patients with HB and APC gene mutation.

Imaging benign hepatocellular tumors: atypical forms and diagnostic traps

Management of patients with a benign hepatocellular tumor relies largely on imaging data; the diagnosis of focal nodular hyperplasia (FNH) must be made with certainty using MRI, because no other clinical or laboratory data can help diagnosis. It is also essential to identify adenomas to manage them appropriately. The radiological report in these situations is therefore of major importance. However, there are diagnostic traps. The aim of this paper is to present the keys to the diagnosis of benign lesions and to warn of the main diagnostic pitfalls.

Expression of genes involved in xenobiotic metabolism and transport in end-stage liver disease: up-regulation of ABCC4 and CYP1B1

BACKGROUND

Expression of drug-metabolizing enzymes and drug transporters in liver is mainly regulated by a system of nuclear receptors. The aim of the current study was to investigate the expression of nuclear receptors, as well as these enzymes and transporters, in liver samples from patients suffering from end-stage liver disease of various etiologies (HCV infection, alcohol liver disease, and primary sclerosis cholangitis).

METHODS

Gene expression was measured using quantitative real-time PCR with surgical specimens from livers of patients with end-stage liver disease, and non-tumoral liver tissue that served as control.

RESULTS

Our study confirmed that the expression of most phase I enzymes is suppressed in end-stage liver disease, and is correlated with a decrease in NR1I2 and NR1I3, the main regulators of xenobiotic metabolism. While mRNA levels of phase II enzymes were generally unchanged, some ABC transporters were up-regulated. The most spectacular increases in expression were observed with ABCC4 (MRP4) - at the mRNA level, and CYP1B1 - at both the mRNA and protein levels. We also demonstrated that IL-6 can induce CYP1B1 expression independently of CYP1A1, in a human hepatocellular liver carcinoma cell line.

CONCLUSIONS

As CYP1B1 is an enzyme which converts various substrates into carcinogenous metabolites, its overexpression in liver may be one of the factors increasing the risk of hepatic cancers in patients with liver disease. CYP1A1 and CYP1B1 are often referred to as model AHR target genes, but CYP1A1 was down-regulated in diseased liver samples. This points to the existence of differences in regulation of these two genes.

Diagnostic Approach to Hepatic Mass Lesions and Role of Immunohistochemistry

This review provides an overview of various hepatic mass lesions and a practical diagnostic approach, including most recent immunohistochemical stains used in clinical practice. A wide variety of benign and malignant lesions present as hepatic masses, and the differential diagnosis varies. In cirrhotic liver, the commonest malignant tumor is hepatocellular carcinoma (HCC), which needs to be differentiated from macroregenerative nodules, dysplastic nodules, and other tumors. The differential diagnosis of lesions in noncirrhotic liver in younger patients includes hepatic adenoma (HA), focal nodular hyperplasia (FNH), HCC, and other primary hepatic neoplasms and metastases. In older populations, metastases remain the most common mass lesions.

[Immunophenotypic classification of 3 cases of hepatocellular adenoma. Differential diagnosis with focal nodular hyperplasia]

Interest in adenomas has been renewed by the discovery of the molecular changes in these tumors. The latest World Health Organization publication on gastrointestinal tract tumors (2010) includes four types of hepatic adenomas, which are well characterized immunohistochemically, genotypically and phenotypically. In these tumors, medical history and morphological behavior play an important role in determining the risk of malignancy, mainly in adenomas with a b-catenin mutation. The presence of steatosis, inflammation, vascular changes linked to response to L-FABP, serum amyloid A, and glutamyl synthetase help to classify these tumors into four groups: hepatocellular adenomas with the HNF1A mutation (H-HCA), those with the b-catenin mutation (b-HCA), inflammatory HCA (IHCA), and HCA without markers. The absence of glypican 3 expression, HSP 70 and perivenular mapping of glutamyl synthetase helps to distinguish these tumors from well differentiated hepatocellular carcinoma. We describe the clinical, morphological and immunophenotypic features of three patients diagnosed with hepatic adenomas in a 2-year period.

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.

Focal Nodular Hyperplasia and Hepatocellular Adenoma around the World Viewed through the Scope of the Immunopathological Classification

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are benign hepatocellular tumors. The risk of bleeding and malignant transformation of HCA are strong arguments to differentiate HCA from FNH. Despite great progress that has been made in the differential radiological diagnosis of the 2 types of nodules, liver biopsy is sometimes necessary to separate the 2 entities. Identification of HCA subtypes using immunohistochemical techniques, namely, HNF1A-inactivated HCA (35-40%), inflammatory HCA (IHCA), and beta-catenin-mutated inflammatory HCA (b-IHCA) (50-55%), beta-catenin-activated HCA (5-10%), and unclassified HCA (10%) has greatly improved the diagnostic accuracy of benign hepatocellular nodules. If HCA malignant transformation occurs in all HCA subgroups, the risk is by far the highest in the β -catenin-mutated subgroups (b-HCA, b-IHCA). In the coming decade the management of HCA will be more dependent on the identification of HCA subtypes, particularly for smaller nodules (<5 cm) in terms of imaging, follow-up, and resection.

Molecular classification of hepatocellular adenomas

Hepatocellular adenomas (HCAs) are benign tumors developed in normal liver most frequently in women before menopause. HCAs lead to diagnostic pitfalls and several difficulties to assess the risk of malignant transformation in these young patients. Recent advances in basic knowledge have revealed a molecular classification related to risk factors, pathological features, and risk of transformation in hepatocellular carcinoma. Three major molecular pathways have been identified altered in specific HCA subgroups that are defined by either (1) inactivation of hepatocyte nuclear factor 1A (HNF1A) transcription factor, (2) activation of the WNT/β-catenin by CTNNB1 mutations, or (3) activation of the IL6/STAT3 pathway by somatic mutation of IL6ST, GNAS, or STAT3. Here, we will review the different molecular classes of HCA.

Life-Threatening Complications of Hormonal Contraceptives: A Case History

We present a case with the rare combination of thrombotic and hemorrhagic complications of oral contraceptives. A healthy 40-year-old woman suffered from cardiac arrest due to massive pulmonary embolism, caused by oral contraceptives and immobilization during a flight. After successful resuscitation, obstructive shock necessitated thrombolysis and thereafter heparin. Anticoagulation was complicated by internal bleeding from contraceptive related hepatic adenoma. She underwent arterial embolisation, and anticoagulation was continued. On day 18, she was discharged in a good condition. Hepatic adenomas are a potential source of internal bleeding in women using oral contraceptives requiring anticoagulation. Signs of internal bleeding in such patients should prompt immediate abdominal ultrasound examination.

Benign hepatocellular tumors in children: focal nodular hyperplasia and hepatocellular adenoma

Benign liver tumors are very rare in children. Most focal nodular hyperplasia (FNH) remain sporadic, but predisposing factors exist, as follows: long-term cancer survivor (with an increasing incidence), portal deprivation in congenital or surgical portosystemic shunt. The aspect is atypical on imaging in two-thirds of cases. Biopsy of the tumor and the nontumoral liver is then required. Surgical resection will be discussed in the case of large tumors with or without symptoms. In the case of associated vascular disorder with portal deprivation, restoration of the portal flow will be discussed in the hope of seeing the involution of FNH. HepatoCellular Adenoma (HCA) is frequently associated with predisposing factors such as GSD type I and III, Fanconi anemia especially if androgen therapy is administered, CPSS, and SPSS. Adenomatosis has been reported in germline mutation of HNF1- α . Management will depend on the presence of a predisposing factor and may include metabolic control, androgen therapy withdrawn, or closure of the shunt when appropriate. Surgery is usually performed on large lesions. In the case of adenomatosis or multiple lesions, surgery will be adapted. Close followup is required in all cases.

A serum amyloid A-positive hepatocellular neoplasm arising in alcoholic cirrhosis: a previously unrecognized type of inflammatory hepatocellular tumor

Hepatocellular adenoma usually arises in the absence of significant fibrosis. Herein, we report seven patients with serum amyloid A-positive hepatocellular neoplasm, which shares features with inflammatory hepatocellular adenoma arising in alcoholic cirrhosis. Seven patients (two women and five men, age range 41-67 years) with hypervascular hepatocellular nodules associated with alcoholic cirrhosis were retrieved from our pathological files (1997-2011). The hepatocellular nodules were multiple (>3) in all patients and 17 nodules were histologically examined. We surveyed the immunoreactivity for serum amyloid A, glutamine synthetase, and glypican-3 in the hepatocellular nodules and control lesions, including 5 focal nodular hyperplasia, 18 dysplastic nodules, and 54 hepatocellular carcinomas in various background diseases. In all, 15 of 17 nodules showed strong and distinct immunoreactivity for serum amyloid A, sharing features with inflammatory hepatocellular adenoma. The serum amyloid A-positive hepatocellular neoplasms showed increased cellular density, inflammatory infiltrate, sinusoidal dilatation, and ductular reaction to various degrees. Although about a half of dysplastic nodules and hepatocellular carcinomas showed focal immunoreactivity for serum amyloid A, the extent of serum amyloid A expression was significantly higher in serum amyloid A-positive hepatocellular neoplasms, than in control nodules. The serum amyloid A-positive hepatocellular neoplasms did not show the overexpression of glutamine synthetase or immunoreactivity for glypican-3. In contrast, most hepatocellular carcinomas showed the overexpression of glutamine synthetase and immunoreactivity for glypican-3, irrespective of background diseases. In conclusion, this study highlights a characteristic group of hepatocellular neoplasms arising in alcoholic cirrhosis, which share features with inflammatory hepatocellular adenomas. These serum amyloid A-positive hepatocellular neoplasms may be a new type of inflammatory hepatocellular tumors in alcoholic patients.

Co-existence of hepatocellular adenoma and focal nodular hyperplasia in a young female

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HA) are both benign hepatocellular lesions, presenting mainly in women of childbearing age in non-cirrhotic, non-fibrotic livers. Simultaneous occurrence of these two lesions is extremely rare. We herein report a case of a young female without any predisposing risk factors who presented to our emergency department complaining of acute abdominal pain. Imaging studies revealed a 6 cm lesion in the right hepatic lobe and a 2.5 cm lesion in the left hepatic lobe, respectively. In view of the patient's symptoms and lack of a confirmed diagnosis based on imaging, we performed a bisegmentectomy V-VI and a wedge resection of the lesion in segment III by laparotomy. Postoperative course was uneventful and the patient was discharged on the fourth postoperative day. The pathology report demonstrated an HA in segments V-VI and FNH in segment III, respectively. Six months later, the patient remains asymptomatic with normal liver function tests, ultrasound and magnetic resonance imaging follow-up. To our best knowledge, this is the first case to describe simultaneous occurrence of HA and FNH without the presence of any known risk factors for these entities. The uncertainty in diagnosis and acuteness of presenting symptoms were established criteria for prompt surgical intervention.

MR findings of steatotic focal nodular hyperplasia and comparison with other fatty tumours

OBJECTIVES

To correlate MR findings with pathology in steatotic FNHs and to compare the MR findings with those of other fatty tumours developed on noncirrhotic liver in a consecutive series of resected lesions.

METHODS

Our population included resected FNH with intralesional steatosis (n = 25) and other resected fatty tumours selected as controls (hepatocellular adenomas and angiomyolipomas, n = 34). Lesions were classified into three groups: those with typical FNH without (group 1) or with (group 2) fat on MR and those with atypical lesions (group 3). In group 3, diagnostic criteria for other fatty tumours were applied.

RESULTS

There were 9 lesions in group 1 (15.3 %), 4 in group 2 (16.8 %) and 46 in group 3 (77.9 %). Group 3 contained 12 FNHs (26 %) and all the other fatty tumours. In group 3, the association of lesion homogeneity, signal intensity similar to or slightly different from adjacent liver on in-phase T1- and T2-weighted sequences, and strong arterial enhancement was observed in 7/12 (58 %) of steatotic FNHs and 3/34 (9 %) of other tumours.

CONCLUSION

On MR, fat within a typical FNH should not reduce the diagnostic confidence. We recommend further investigations including liver biopsy if necessary when fatty tumours exhibit atypical MR findings.

Incidence and etiology of new liver lesions in pediatric patients previously treated for malignancy

OBJECTIVE

The purpose of this study was to retrospectively evaluate the time course, cause, and imaging characteristics of all new liver lesions in pediatric patients with a previously treated malignancy.

MATERIALS AND METHODS

Our hospital cancer registry was used to identify patients between 1980 and 2005 who met the following criteria: solid tumor, survival > 2 years after diagnosis, no liver lesions at a posttreatment baseline, and cross-sectional imaging follow-up of > 2 years. Final dictated reports of all cross-sectional imaging examinations including the abdomen were reviewed for any mention of new liver lesions. Positive reports were followed by consensus review of the images and clinical data. Patients were divided into three groups: those with suspected or proven focal nodular hyperplasia (FNH), those with suspected or proven metastases, and those with other lesions. An exact Wilcoxon test was used to evaluate the differences between the groups.

RESULTS

Of 967 patients who met the initial inclusion criteria, 273 had adequate follow-up to be included in the study. Forty-six patients (16.8%) developed new liver lesions during the study period, and 14 of those 46 were classified into the FNH group (30.4%) and seven were classified into the metastasis group (15.2%). A significant difference was found in the median time to the development of FNH versus metastasis and other lesions (FNH, 92.9 months; metastasis, 43.2 months; other lesions, 18.5 months; p < 0.0001). A significant difference was also seen in the median length of follow-up between the groups (FNH, 115.6 months; metastasis, 57 months; other lesions, 50.8 months; p = 0.002). The imaging features of the groups also differed.

CONCLUSION

The most common liver lesion encountered in pediatric patients previously treated for malignancy was FNH, which occurred farther from the time of diagnosis and had different imaging characteristics from both metastases and other liver lesions.

Hepatocellular adenoma: evaluation with contrast-enhanced ultrasound and MRI and correlation with pathologic and phenotypic classification in 26 lesions

Purpose. To review the contrast-enhanced ultrasonographic (CEUS) and magnetic resonance (MR) imaging findings in 25 patients with 26 hepatocellular adenomas (HCAs) and to compare imaging features with histopathologic results from resected specimen considering the new immunophenotypical classification. Material and Methods. Two abdominal radiologists reviewed retrospectively CEUS cineloops and MR images in 26 HCA. All pathological specimens were reviewed and classified into four subgroups (steatotic or HNF 1α mutated, inflammatory, atypical or β-catenin mutated, and unspecified). Inflammatory infiltrates were scored, steatosis, and telangiectasia semiquantitatively evaluated. Results. CEUS and MRI features are well correlated: among the 16 inflammatory HCA, 7/16 presented typical imaging features: hypersignal T2, strong arterial enhancement with a centripetal filling, persistent on delayed phase. 6 HCA were classified as steatotic with typical imaging features: a drop out signal, slight arterial enhancement, vanishing on late phase. Four HCA were classified as atypical with an HCC developed in one. Five lesions displayed important steatosis (>50%) without belonging to the HNF1α group. Conclusion. In half cases, inflammatory HCA have specific imaging features well correlated with the amount of telangiectasia and inflammatory infiltrates. An HCA with important amount of steatosis noticed on chemical shift images does not always belong to the HNF1α group.

Hepatocellular adenoma in glycogen storage disorder type I: a clinicopathological and molecular study

AIMS

  Glycogen storage disease type I is a metabolic disorder resulting from deficiency of the glucose-6-phosphate complex. Long-term complications include the development of hepatocellular adenoma (HCA). In this retrospective study, our aim was to reclassify according to geno-phenotypic characteristics nodular lesions identified in hepatectomy specimens of such patients transplanted between 1998 and 2008 at our institution.

METHODS AND RESULTS

  Clinicopathological data of seven consecutive transplanted patients with glycogen storage disease type I were reviewed. Liver nodules were re-examined histologically and by immunohistochemistry. Molecular analysis was performed additionally in a case with specific features. Four patients had multiple tumours. We concluded that 26 of 38 nodules available for study had features of inflammatory hepatocellular adenomas, seven comprised adenomas not otherwise specified and five were found to be focal nodular hyperplasia.

CONCLUSIONS

  Further studies are needed to clarify the pathogenesis of hepatocellular adenomas in glycogen storage disease; in particular to determine whether they share abnormal metabolic pathways with inflammatory adenomas in the general population. Testing for acute phase proteins may be a helpful tool in the early detection of HCA in such patients. Finally, there is a need to further define their risk of malignant transformation, in relation to age and possible cofactors.

Appearance of hepatocellular adenomas on gadoxetic acid-enhanced MRI

OBJECTIVE

The purpose of this study was to evaluate enhancement characteristics of hepatocellular adenomas (HCAs) using gadoxetic acid as a hepatocyte-specific MR contrast agent.

METHODS

Twenty-four patients with histopathologically proven HCAs were retrospectively identified. MRI consisted of T1- and T2-weighted (w) sequences with and without fat saturation (fs), multiphase dynamic T1-w images, and fs T1-w images during the hepatobiliary phase. Standard of reference was surgical resection (n = 19) or biopsy (n = 5). Images were analysed for morphology and contrast behaviour including signal intensity (SI) measurement on T1-w images normalised to the pre-contrast base line.

RESULTS

In total 34 HCAs were evaluated. All HCAs showed enhancement in the arterial phase; 38 % of HCAs showed reduced contrast enhancement ("wash-out") in the venous phase. All HCAs showed enhancement (SI increase, 56 ± 53 %; P <0.001) in the hepatobiliary phase, although liver uptake was stronger (96 ± 58 %). Thus, 31 of all HCAs (91 %) appeared hypointense to the surrounding liver in the hepatobiliary phase, while 3 out of 34 lesions were iso-/hyperintense.

CONCLUSIONS

Gadoxetic acid accumulates in HCAs in the hepatobiliary phase, although significantly less than in surrounding liver. Thus, HCA appears in the vast majority of cases as a hypointense lesion on hepatobiliary phase images.

KEY POINTS

• Magnetic resonance-specific contrast agents are now available for hepatic imaging. • Hepatocellular adenomas enhance with gadoxetic acid as in previous CT/MRI experience. • Enhancement during the hepatobiliary phase is less in HCAs than in liver. • Typical HCAs appear as hypointense lesions on T1-w hepatobiliary phase images. • True hyperintense HCA enhancement can occasionally occur during the hepatobiliary phase.

Hepatocellular adenoma and focal nodular hyperplasia: value of gadoxetic acid-enhanced MR imaging in differential diagnosis

PURPOSE

To retrospectively evaluate the utility of gadoxetic acid-enhanced magnetic resonance (MR) imaging in the differential diagnosis of hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH).

MATERIALS AND METHODS

This study had institutional review board approval; the requirement for informed consent was waived. Eighty-two patients (58 patients with FNH and 24 patients with HCAs) with 111 lesions were included in the study. There were 74 female patients and eight male patients (mean age, 41.9 years±13.2 [standard deviation]; age range, 11-78 years). Two readers reviewed all images in terms of signal intensity (SI) features on unenhanced, dynamic, and hepatobiliary phase images. For quantitative analysis, contrast enhancement ratio (CER), lesion-to-liver contrast (LLC), and SI ratio on dynamic and hepatobiliary phase images were calculated.

RESULTS

The CER of FNH in the arterial phase (mean, 94.3%±33.2) was significantly higher than that of HCAs (mean, 59.3%±28.1) (P<.0001). During the hepatobiliary phase, the LLC of FNH showed minimally positive values (mean, 0.05±0.01) and that of HCAs demonstrated strong negative values (mean, -0.67±0.24) (P<.0001). The area under the receiver operating characteristic curve of the hepatobiliary phase SI ratio for differentiation of the two tumors was 0.97, and a sensitivity of 92% and specificity of 91% were found with a cutoff value of 0.87. Among six FNH lesions that showed atypical hypointensity during the hepatobiliary phase, four had a large central scar, one contained a substantial fat component, and one had abundant radiating fibrous septa. Three HCAs were isointense during the hepatobiliary phase owing to severe hepatic steatosis.

CONCLUSION

Gadoxetic acid-enhanced MR imaging facilitates the differentiation of FNH from HCA.

[Focal nodular hyperplasia in a 12-year-old boy: case report and considerations]

BACKGROUND

Focal nodular hyperplasia (FNH) is a benign hepatic tumor of unknown origin. It is only observed rarely in children (approximately 1-2% of all pediatric liver tumors).

CASE REPORT

A 12-year-old boy who suffered from infectious mononucleosis with liver involvement and hepatomegaly underwent a sonographic scan of the liver at an external hospital 3 months after the infection disappeared which revealed a tumor of the left hepatic lobule. Subsequent further examination (abdominal CT and MRT scans) confirmed the diagnosis of a highly vascularized mass about 10 cm in diameter, suspicious for FNH. Due to the high vascularization no biopsy was performed. A preoperative angiographic coiling and complete surgical resection was carried out because of the size and morphologic uncertainty. The diagnosis of FNH was confirmed by histological examination. The annual sonographic examination at follow-up has been uneventful for a 4-year period.

CONCLUSIONS

Due to the rarity the diagnosis of FNH in children can be difficult leading to differential diagnostic problems. Due to the risk of bleeding in larger size tumors a biopsy is a point of controversy. Complete resection and histopathological examination of FNHs in childhood is a mandatory therapeutic option, which may be indicated in large tumors or, as in the present case tumors of uncertain biological behaviour.

Overview of hepatocellular adenoma in Japan

Hepatocellular adenoma (HCA) is generally a benign hepatocellular tumor arising in a nonfibrotic/cirrhotic liver, and recently four major subgroups were identified based on genotype and phenotype classification from Europe. HCA is rare in Asian countries including Japan, and there have been few studies regarding the subgroups of HCA in Japan. We surveyed subgroups of HCA in 13 patients (7 women) in Japan, based on the phenotypic classification. As results, we identified 2 hepatocyte nuclear factor (HNF) 1α-inactivated HCAs (15%), two β-catenin-activated HCAs (15%), 5 inflammatory HCAs (39%), and 4 unclassified HCAs (29%). The use of oral contraceptives was found only in 2 unclassified HCAs (29%). Rather low percentage of female patients and use of oral contraceptives appear to be common clinicopathological features in Japan and also East Asian countries. Furthermore, a group of possible inflammatory HCAs characterized by strong immunoreactivity for serum amyloid A (SAA) was found in patients with alcoholic cirrhosis. The inflammatory HCA/SAA-positive hepatocellular neoplasm in alcoholic cirrhosis may be a new entity of HCA, which may have potential of malignant transformation. Further studies are needed to clarify genetic changes, monoclonality, and pathogenesis of this new type of hepatocellular neoplasm.

Can a decision-making model be justified in the management of hepatocellular adenoma?

During recent years, there was a great development in the area of hepatocellular adenomas (HCA), especially regarding the pathological subtype classification, radiological imaging and management during pregnancy. This review discusses the current knowledge about diagnosis and treatment modalities of HCA and proposes a decision-making model for HCA. A Medline search of studies relevant to epidemiology, histopathology, complications, imaging and management of HCA lesions was undertaken. References from identified articles were hand-searched for further relevant articles.