Unclassified hepatocellular adenoma with beta-catenin mutation: a case report

Hepatocellular Adenoma in an Infant With Burn-McKeown Syndrome: Report of a Case

Hepatocellular adenomas (HCA) in infants are exceedingly rare with only 5 cases reported to the best of our knowledge, all of them preceding the classification of HCA. Here we present an autopsy case of a 9-month-old girl with Burn-McKeown syndrome with an incidental liver nodule in the right lobe measuring 1.5 cm in greatest dimension. The lesion was composed of an unencapsulated proliferation of hepatocytes with multiple unaccompanied arteries without well-formed portal tracts, and an intact reticulin framework without thickened hepatic plates, findings consistent with an HCA. Glutamine synthetase (GS), lipid fatty acid-binding protein (LFABP), c-reactive protein (CRP), serum amyloid-a (SAA), beta-catenin and CD34 immunostains were performed. GS was diffusely and strongly positive in the lesion, CD34 showed heterogenous staining of sinusoids within the lesion without a well-formed rim from the background liver and beta-catenin was negative for nuclear staining. CRP and SAA were considered negative, and LFABP was retained. Molecular testing showed no CTNNB1 variants and found two tier 3 variants involving CHEK2 and PTEN genes. These findings are consistent with an unclassified HCA (U-HCA) per the 2019 WHO Classification of Tumors, representing the youngest patient reported. This raises the possibility that some HCAs are congenital or develop very early in life, remaining undiagnosed until later in life.

Hepatocellular Adenoma: What We Know, What We Do Not Know, and Why It Matters

In the last 2 decades there has been significant progress in research and diagnosis of hepatocellular adenoma (HCA), resulting in the establishment of a molecular and immunohistological HCA classification. This review aims to fine-tune the current expertise in order to enhance the histopathological diagnostic possibilities, by refining issues that are already known, addressing diagnostic difficulties and identifying still unknown aspects of HCA. We will discuss novel methods to identify HCA subtypes, in particular the sonic hedgehog HCAs and the interpretation of glutamine synthetase patterns for the recognition of beta-catenin mutated HCAs. The major complications of HCAs, bleeding and malignant transformation, will be considered, including the dilemmas of atypical and borderline lesions. Paragraphs on HCAs in different clinical and geographical settings, e.g. pregnancy, cirrhosis and non-western countries are included. The natural history of the different HCA subtypes in relation with age, sex and risk factors is a feature still insufficiently investigated. This is also true for the risks of clinical bleeding and malignant transformation in association with HCA subtypes. As HCA is a relatively rare tumor, a multicenter and multidisciplinary approach across geographical boundaries will be the appropriate method to establish prospective programs to identify, classify and manage HCAs, focusing on several aspects, e.g. etiology, underlying liver disease, complications, regression and growth. Updating what we know, identifying and addressing features that we do not know matters to warrant optimal patient management.