Primary liver cancers, namely, hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), are common in the East, due to the high incidence of chronic viral hepatitis B from Mongolia down to Southeast Asia, and endemic liver fluke infestation in Northeast Thailand, respectively. There are two major challenges concerning the diagnosis of focal liver lesions. First, the liver parenchyma itself often undergoes cirrhosis and gives rise to a spectrum of hepatocellular nodular lesions of variable biologic status; all of which have to be distinguished from HCC. Second, the liver is a common depository for metastases from all parts of the body; and these can mimic the two most important primary liver cancers with their variations and variants, and vice versa.

Small tissue samples of focal liver lesions are almost invariably procured by fine needle aspiration biopsy (FNAB) and/or core needle biopsy (CNB) under imaging guidance in most practices. The morphologic assessment of such samples with the aid of appropriate ancillary tests, such as immunohistochemistry, is the mainstay for the accurate diagnosis of focal liver lesions. The radiologist's diagnostic acumen and skill contribute significantly to the overall diagnostic yield and accuracy.

This book is planned as a highly illustrated practical guide to the morphologic diagnosis of tumors and tumor-like lesions in small tissue samples of the liver. A kaleidoscope of morphologic patterns and cell profiles exist. Often immunohistochemistry is required to define the histogenetic cell type and site of origin for the final definitive diagnosis. Pictures say more than words, tables highlight diagnostic points, and diagnostic algorithms summarize flow of thought. The authors do not aim to be comprehensive and there is intentionally only a mention of molecular pathology. We aim to provide general concepts and roadmaps to facilitate the pattern cum cell profiling-based diagnostic approach to focal liver lesions with matching clinical and radiologic perspectives.