This issue of the American Journal of Surgical Pathology, Reviews and Reports is devoted to recent advances and update in the pathology of the liver. The articles provide insights into the current nomenclature, classification, diagnosis, differential diagnoses, clinical and prognostic aspects of various liver diseases, and lesions that are informative to pathologists in their daily practice.

Hepatocellular adenomas (HCAs) is generally a benign liver neoplasm that typically arises in the noncirrhotic liver; however, malignant transformation does occur, and hence, subtyping is critical. Drs Jung and Liu present a case of HCA that was initially diagnosed as inflammatory HCA on a biopsy and subsequently was confirmed to be β-catenin–activated inflammatory HCA on the resection specimen. They then comprehensively review recent updates on molecular classification and the key histologic features of each subtype and discuss common diagnostic pitfalls.

Over the past decades, hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA) have been recognized to be heterogeneous in morphology, molecular features, and biological behavior. Recent World Health Organization classification describes various histomorphological subtypes of HCC and iCCA, some with characteristic molecular profiles, clinical correlates, and prognostic implications. In their review, Drs Hwang and Kim nicely discuss recently described subtypes of HCC and iCCA: macrotrabecular HCC, steatohepatitic HCC, scirrhous HCC, and small duct iCCA.

Congestive hepatopathy shows a unique pattern of fibrosis, that is, pericentral fibrosis at early stage, which may progress to bridging fibrosis and cirrhosis. Making a diagnosis of congestive hepatopathy and staging its fibrosis are important tasks for pathologists, as patients may undergo liver biopsies before cardiac transplantation to assess the degree of liver fibrosis, which may impact clinical decision-making. Besides patients' own cardiac dysfunction, congestive hepatopathy can also be seen after a Fontan procedure. Drs Gosse and Bosch describe a case of congestive hepatopathy due to altered circulation with a Fontan procedure. They then discuss the fibrosis scoring systems recently described for Fontan-associated liver disease and congestive heart disease–associated hepatopathy.

Combined hepatocellular-cholangiocarcinoma is a rare primary liver tumor with neoplastic components of both hepatocytic and cholangiocytic differentiation within the same tumor. There is recent consensus paper and World Health Organization classification of this unique tumor. Drs Kondo, Akiba, and Yano herein report a case of this tumor and thoughtfully review the terminology, classification, and clinical and pathological characteristics of combined hepatocellular-cholangiocarcinoma and its differential diagnosis.

Hemophagocytic lymphohistiocytosis is a rare disease with a high mortality. Liver involvement is common, with most patients demonstrating acute hepatitis. Therefore, liver biopsies are frequently performed when this entity is suspected. Dr Xiong and colleagues summarize the clinical features of hemophagocytic lymphohistiocytosis, emphasizing its hepatic manifestations. They describe the highly variable histologic patterns and address difficulties encountered by pathologists.

We are extremely grateful to all the contributors for sharing their expertise and knowledge in forming this issue. We hope that the information provides highlights and elucidates the practically encountered lesions in the liver.

Guest Editors