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Background: EUS-guided FNA is one of the few techniques that can obtain cells and tissue from the liver and pancreas. However, the technique remains vulnerable to poor specimen quality and sampling error., Objective: To evaluate the ability of a high-resolution microendoscope (HRME) to visualize the cellular and architectural features of normal and malignant liver and pancreatic tissue ex vivo, to assess the ability of endosonographers to identify normal and neoplastic tissue by using HRME images, and to demonstrate preliminary technical feasibility of in vivo HRME imaging via EUS fine-needle puncture (FNP)., Design: Ex vivo pilot feasibility study in human tissue; in vivo swine model., Setting: Two academic medical centers., Patients: Co-registered HRME images and biopsies were obtained from surgically resected hepatic and pancreatic tissues from 44 patients., Intervention: Images were divided into training (12 images) and test (80 images) sets containing a range of normal and pathologic conditions for each organ. After viewing the training sets, 9 endosonographers attempted to distinguish malignant tissue from normal or benign lesions in the test sets, each of which contained 40 unique images with individual diagnoses from pathology., Main Outcome Measurements: Image acquisition feasibility, ex vivo and in vivo. Ability of endosonographers to recognize features of normal/benign or malignant tissue from the liver and pancreas., Results: Overall, the 9 endosonographers achieved median accuracy figures of 85% in the liver and 90% in the pancreas. The endosonographers with prior experience in reading HRME images achieved accuracy rates between 90% and 95%. Technical feasibility of HRME imaging through a 19-gauge EUS-FNP needle was demonstrated in an in vivo swine model., Limitations: Ex vivo study., Conclusion: High-resolution microendoscopy allows real-time imaging of cellular-level morphology and tissue architecture in the liver and pancreas. The technique appears to have a short learning curve, after which endosonographers achieved high accuracy rates in distinguishing malignant tissue from normal and benign pathology in both organs. Translating this imaging platform to the in vivo setting appears technically feasible., (Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)

Telangiectatic hepatocellular adenoma is a rare, recently recognized subtype of hepatocellular adenoma that is often underrecognized by pathologists. We report a case of hepatocellular carcinoma arising within a pigmented telangiectatic hepatocellular adenoma in a noncirrhotic man with diffuse glutamine synthetase and nuclear β-catenin positivity. This case highlights malignant transformation of telangiectatic adenomas, and describes a previously unreported association between pigment deposition and telangiectatic adenoma. Radiology, gross pathology, and histopathology are shown. Review of the literature with attention to β-catenin and glutamine synthetase staining, malignant transformation, patient characteristics, the presence of Dubin-Johnson-like pigment, and genetic characteristics of telangiectatic adenomas are discussed.