21 Review Article Evolution of the liver biopsy and its future Dhanpat Jain1, Richard Torres2, Romulo Celli1, Jeremy Koelmel3, Georgia Charkoftaki3, Vasilis Vasiliou3 1Department of Anatomic Pathology, 2Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA; 3Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, USA Contributions: (I) Conception and design: D Jain; (II) Administrative support: None; (III) Provision of study material or patients: None; (IV) Collection and assembly of data: None; (V) Data analysis and interpretation: None; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors. Correspondence to: Dhanpat Jain, MD. Professor of Pathology, Yale University School of Medicine, New Haven, CT, USA. Email: [email protected]. Abstract: Liver biopsies are commonly used to evaluate a wide variety of medical disorders, including neoplasms and post-transplant complications. However, its use is being impacted by improved clinical diagnosis of disorders, and non-invasive methods for evaluating liver tissue and as a result the indications of a liver biopsy have undergone major changes in the last decade. The evolution of highly effective treatments for some of the common indications for liver biopsy in the last decade (e.g., viral hepatitis B and C) has led to a decline in the number of liver biopsies in recent years. At the same time, the emergence of better technologies for histologic evaluation, tissue content analysis and genomics are among the many new and exciting developments in the field that hold great promise for the future and are going to shape the indications for a liver biopsy in the future. Recent advances in slide scanners now allow creation of “digital/ virtual” slides that have image of the entire tissue section present in a slide [whole slide imaging (WSI)]. WSI can now be done very rapidly and at very high resolution, allowing its use in routine clinical practice. In addition, a variety of technologies have been developed in recent years that use different light sources and/or microscopes allowing visualization of tissues in a completely different way. One such technique that is applicable to liver specimens combines multiphoton microscopy (MPM) with advanced clearing and fluorescent stains known as Clearing Histology with MultiPhoton Microscopy (CHiMP). Although it has not yet been extensively validated, the technique has the potential to decrease inefficiency, reduce artifacts, and increase data while being readily integrable into clinical workflows. Another technology that can provide rapid and in-depth characterization of thousands of molecules in a tissue sample, including liver tissues, is matrix assisted laser desorption/ionization (MALDI) mass spectrometry. MALDI has already been applied in a clinical research setting with promising diagnostic and prognostic capabilities, as well as being able to elucidate mechanisms of liver diseases that may be targeted for the development of new therapies. The logical next step in huge data sets obtained from such advanced analysis of liver tissues is the application of machine learning (ML) algorithms and application of artificial intelligence (AI), for automated generation of diagnoses and prognoses. This review discusses the evolving role of liver biopsies in clinical practice over the decades, and describes newer technologies that are likely to have a significant impact on how they will be used in the future. Keywords: Liver biopsy; matrix assisted laser desorption imaging (MALDI); Clearing Histology with MultiPhoton Microscopy (CHiMP); whole slide imaging (WSI) Received: 12 January, 2020; Accepted: 19 March, 2020; Published: 05 April 2021. doi: 10.21037/tgh.2020.04.01 View this article at: http://dx.doi.org/10.21037/tgh.2020.04.01 © Translational Gastroenterology and Hepatology. All rights reserved. Transl Gastroenterol Hepatol 2021;6:20 | http://dx.doi.org/10.21037/tgh.2020.04.01 Page 2 of 21 Translational Gastroenterology and Hepatology, 2021 Introduction lesion is difficult to approach by other means. Liver biopsies (needle or wedge) can also be obtained intra-operatively Since its original description by Ehrlich in 1883, the whenever liver disease is suspected or suspicious lesions clinical role of liver biopsy has changed dramatically over are identified. While needle biopsies provide a core of the years (1). Initially, it was used for determination of liver parenchyma, wedge biopsies provide a “wedge” of glycogen stores in the livers of diabetic patients while in liver tissue taken from it surface and are much larger. the ensuing years, its indications have become more diverse In many instances, an abnormal appearance of the liver and numerous (2). It took a few decades for the liver biopsy during surgery for an unrelated procedure (most often to be accepted as a standard medical procedure by the cholecystectomy) is the first indication of an underlying medical community. Only after Menghini described “one- liver disease. Liver biopsies harvested intra-operatively second needle biopsy of the liver” in 1958 did the procedure have the added advantage of obtaining tissue samples from come into more widespread clinical use (2). While liver grossly visible/suspicious lesions. However, these wedge biopsies are commonly used to evaluate a wide variety of biopsies are often suboptimal for assessment of liver fibrosis medical disorders, including neoplasms and post-transplant and/or inflammation due to the preponderance of Glissen’s complications, its use is being impacted by improved capsule, wider portal tracts in subcapsular area, and frequent clinical diagnosis of disorders, and non-invasive methods for (but inconsequential) surgically-induced hepatitis (8). evaluating liver tissue. Nevertheless, liver biopsies continue Therefore, needle biopsy should be the technique of choice to provide highly valuable information for clinical and at laparotomy or be used in addition to a wedge biopsy. research purposes. This review considers the evolving role Once obtained, liver tissue needs to be triaged for of liver biopsies in clinical practice over the decades, and various special procedures e.g., electron microscopy, describes technologies that are likely to have a significant microbiological cultures, immunofluorescence studies or impact on how they will be used in the future. flow cytometry, based on the clinical differential diagnosis. Liver tissue can be obtained for clinical analysis in Thus, it is very important that critical clinical details (e.g., several ways, including percutaneous, transjugular, liver enzymes, history of medications/toxin exposure, laparoscopic, and intra-operative approaches. Each of these viral and autoimmune serology) and a clinical differential have advantages and disadvantages. The percutaneous liver diagnosis be communicated to the pathologist so that biopsy technique remains the standard practice in most appropriate tissue triage and special procedures can be medical centers. Whenever a percutaneous needle biopsy undertaken without loss of time. is contraindicated (e.g., presence of significant ascites or Histological examination is an essential tool for the coagulopathy), a transjugular needle biopsy is preferred. evaluation of patients with liver disease, particularly those An important advantage of the transjugular approach is the with persistent unexplained liver function abnormalities. ability to obtain intrahepatic portal pressures that aid in Most pathology labs will routinely perform trichrome, the diagnosis and management of select groups of patients, hematoxylin and eosin (H&E), reticulin, iron and D-PAS particularly those with cirrhosis (3). However, transjugular (periodic acid-Schiff stain after diastase digestion) biopsies often render smaller and fragmented tissue stains on liver biopsies for clinical evaluation of a liver samples, making pathologic assessment somewhat difficult. disorder. Under certain circumstances, special sample Percutaneous or transjugular biopsies are used to obtain preparation and fixation may be required, such as placing samples from patients suffering from disorders that involve the tissue in appropriate culture medium (for suspected a diffuse change in the liver (3,4). By contrast, image-guided infections), processing in metal-free containers (for metal needle biopsies are necessary for focal diseases/lesions (5,6). quantification), fixation in glutaraldehyde (for electron Laparoscopic liver biopsy enables the gross features of microscopy), using frozen tissue (for Oil red O stain for the the liver to be assessed prior to taking the biopsy. During estimation of microvesicular fat), or simply “RUSH/STAT” laparoscopy apart from needle core biopsy, a wedge of liver processing in critically ill patients (e.g., those with fulminant tissue (wedge biopsy) can be obtained. Due to the nature of liver failure or the post-transplant situation) (2). Routine surgery involved, laparoscopic liver biopsy has added costs histological evaluation of liver biopsies involves assessment and the potential for more complications (7). As such, it is of inflammation, cellular changes involving hepatocytes and used in select settings at most centers e.g., when laparoscopy bile ducts, abnormal accumulation of various substances, is being anyway performed for another indication or the the extent of the liver injury, and/or fibrosis. The liver © Translational Gastroenterology and Hepatology. All rights reserved.