Focal liver lesions (FLLs) have become an increasingly common finding on abdominal imaging, especially asymptomatic and incidental liver lesions. Gastroenterologists and hepatologists often see these patients in consultation and make recommendations for management of multiple types of liver lesions, including hepatocellular adenoma, focal nodular hyperplasia, hemangioma, and hepatic cystic lesions including polycystic liver disease. Malignancy is important to consider in the differential diagnosis of FLLs, and healthcare providers must be familiar with the diagnosis and management of FLLs. This American College of Gastroenterology practice guideline uses the best evidence available to make diagnosis and management recommendations for the most common FLLs.

Benign liver tumours (BLT) are increasingly diagnosed as incidentalomas. Clinical implications and management vary across and within the different types of BLT. High-quality clinical practice guidelines are needed, because of the many nuances in tumour types, diagnostic modalities, and conservative and invasive management strategies. Yet, available observational evidence is subject to interpretation which may lead to practice variation. Therefore, we aimed to systematically search for available clinical practice guidelines on BLT, to critically appraise them, and to compare management recommendations.
A scoping review was performed within MEDLINE, EMBASE, and Web of Science. All BLT guidelines published in peer-reviewed, and English language journals were eligible for inclusion. Clinical practice guidelines on BLT were analysed, compared, and critically appraised using the Appraisal of Guidelines, Research and Evaluation (AGREE II) checklist regarding hepatic haemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA). Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations (PRISMA) for scoping reviews were adhered to.
The literature search yielded unique 367 papers, 348 were excluded after screening of title/abstract, and 16 after full-text screening. Three guidelines were included: the American College of Gastroenterology (ACG; 2014), Brazilian Society of Hepatology (SBH; 2015), and European Association for the Study of the Liver (EASL; 2016). There was no uniformity in the assessment methods for grading and gravity of recommendations between guidelines. Among observed differences were: (1) indications for biopsy in all three tumours; (2) advices on contraceptive pills and follow-up in FNH and HCA; (3) use of an individualised approach to HCA; (4) absence of recommendations for treatment of HCA in men; and (5) approaches to HCA subtype identification on magnetic resonance imaging.
Recognising differences in recommendations can assist in harmonisation of practice standards and identify unmet needs in research. This may ultimately contribute to improved global patient care.

Hepatocellular adenoma (HA) is a rare benign liver tumor with increasing incidence affecting young women. In the last years, much has changed in diagnosis, classification, and treatment, due to the identification of different molecular subtypes. With the evolving knowledge, especially on molecular characteristics of the disease, we are far from a consensus of how to deal with such a multifaceted benign disease METHODS: In the last 20 years, we have treated 134 patients with HA with a mean age of 28 years, being 126 women. Fifty patients had a history of abdominal pain and 13 patients had an acute episode of pain due to rupture and bleeding. Until 2009, adenomas larger than 4 cm in diameter were resected, regardless of gender. From 2010 to 2016, only adenomas larger than 5 cm were referred for surgical treatment. Since 2016, resection was indicated in all female patients with non-steatotic adenomas larger than 5 cm and all adenomas in men.
One hundred twenty-four patients were submitted to resection, being in 21 major resections. Since 2010, 74% of resections were done laparoscopically. Patients with ruptured adenomas were treated with transarterial embolization. Morbidity rate was 8.1% with no mortality. Authors discuss point-by-point all the aspects and presentations of the disease and the best approach. We proposed a therapeutic guideline based on the best available evidence and in our experience.
Due to the complexity of the disease, the treatment of HA is one the best examples of an individualized approach.

Rapid advances in molecular and anatomic pathology have greatly improved our understanding of hepatocellular adenomas. Principle among them is a clinically relevant, histology-based classification that identifies hepatic adenomas at greatest risk for malignant transformation. This new classification system has led to general consensus on the major subtypes of hepatic adenomas. However, controversy remains regarding how to incorporate less common types of hepatic adenomas into the classification system and how to incorporate adenoma subtyping into clinical care. This article provides an in-depth review of how adenomas are classified, with a focus on the current rationale, the consensus, and controversies.

OBJECTIVE: To develop a consensus and provide updated recommendations on liver MR imaging and the clinical use of liver-specific contrast agents.
METHODS: The European Society of Gastrointestinal and Abdominal Radiology (ESGAR) formed a multinational European panel of experts, selected on the basis of a literature review and their leadership in the field of liver MR imaging. A modified Delphi process was adopted to draft a list of statements. Descriptive and Cronbach\'s statistics were used to rate levels of agreement and internal reliability of the consensus.
RESULTS: Three Delphi rounds were conducted and 76 statements composed on MR technique (n = 17), clinical application of liver-specific contrast agents in benign, focal liver lesions (n = 7), malignant liver lesions in non-cirrhotic (n = 9) and in cirrhotic patients (n = 18), diffuse and vascular liver diseases (n = 12), and bile ducts (n = 13). The overall mean score of agreement was 4.84 (SD ±0.17). Full consensus was reached in 22 % of all statements in all working groups, with no full consensus reached on diffuse and vascular diseases.
CONCLUSIONS: The consensus provided updated recommendations on the methodology, and clinical indications, of MRI with liver specific contrast agents in the study of liver diseases.
CONCLUSIONS: • Liver-specific contrast agents are recommended in MRI of the liver. • The hepatobiliary phase improves the detection and characterization of hepatocellular lesions. • Liver-specific contrast agents can improve the detection of HCC.

OBJECTIVE: Liver-specific MRI is a fast-growing field, with technological and protocol advancements providing more robust imaging and allowing a greater depth of information per examination. This article reports the evidence for, and expert thinking on, current challenges in liver-specific MRI, as discussed at the 7th International Forum for Liver MRI, which was held in Shanghai, China, in October 2013.
METHODS: Topics discussed included the role of gadoxetic acid-enhanced MRI in the differentiation of focal nodular hyperplasia from hepatocellular adenoma and small hepatocellular carcinoma (HCC) from small intrahepatic cholangiocarcinoma (in patients with chronic liver disease), the differentiation of low-grade dysplastic nodule (DN) from pre-malignant high-grade DN and early HCC, and treatment planning and assessment of treatment response for patients with HCC and colorectal liver metastasis. Optimization of the gadoxetic acid-enhanced MRI protocol to gain robust arterial and hepatobiliary phase images was also discussed.
CONCLUSIONS: Gadoxetic acid-enhanced MRI demonstrates added value for the detection and characterization of focal liver lesions and shows promise in a number of new indications, including regional liver functional assessment and patient monitoring after therapy; however, more data are needed in some areas, and further developments are needed to translate cutting-edge techniques into clinical practice.
CONCLUSIONS: Liver-specific MRI is a fast-growing field, with many technological and protocol advancements. Gadoxetic acid-enhanced MRI demonstrates value for detecting and characterizing focal liver lesions. Gadoxetic acid-enhanced MRI shows promise in regional functional assessment and patient monitoring. Further developments are needed to translate cutting-edge techniques into clinical practice.

Hepatocellular adenomas are rare benign nodules developed mainly in women taking oral contraceptives. They are solitary or multiple. Their size is highly variable. There is no consensus in the literature for their management except that once their size exceeds 5 cm nodules are taken out to prevent 2 major complications: bleeding and malignant transformation. There are exceptions particularly in men where it is recommended to remove smaller nodules. Since the beginning of this century, major scientific contributions have unveiled the heterogeneity of the disease. HCA are composed of four major subtypes. HNF1A (coding for hepatocyte nuclear factor 1a) inactivating mutations (H-HCA); inflammatory adenomas (IHCA); the β-catenin-mutated HCAs (β-HCA) and unclassified HCA (UHCA) occurring in 30-40%, 40-50%, 10-15% and 10% of all HCA, respectively. Half of β-HCAs are also inflammatory (β-IHCA). Importantly, β-catenin mutations are associated with a high risk of malignant transformation. HCA subtypes can be identified on liver tissue, including biopsies using specific immunomarkers with a good correspondence with molecular data. Recent data has shown that TERT promoter mutation was a late event in the malignant transformation of β-HCA, β-IHCA. Furthermore, in addition to β-catenin exon 3 mutations, other mutations do exist (exon 7 and 8) with a lower risk of malignant transformation. With these new scientific informations, we have the tools to better know the natural history of the different subtypes, in terms of growth, disappearance, bleeding, malignant transformation and to investigate HCA in diseased livers (vascular diseases, alcoholic cirrhosis). A better knowledge of HCA should lead to a more rational management of HCA. This can be done only if the different subspecialties, including hepatologists, liver pathologists, radiologists and surgeons work altogether in close relationship with molecular biologists. It is a long way to go.

Contrast-enhanced ultrasound (CEUS) is a well established diagnostic imaging technique for a variety of indications and applications. One of the most important applications is in the liver where it is frequently a first-line technique for the detection and diagnosis (characterization) of focal liver lesions (FLLs). In this setting the accurate differentiation of benign lesions from malignant lesions is critical to ensure that the patient undergoes the appropriate therapeutic option. In this article the role of CEUS in the characterization of FLLs is described on the basis of recently published guidelines, in particular in terms of the enhancement patterns of the most common FLLs, e. g. hemangioma, focal nodular hyperplasia, hepatocellular adenoma and their differentiation from malignant lesions.