Chapter 11 - Neoplasms and Nodules

Abstract

A major indication for liver biopsy is the diagnosis of primary and secondary tumours. The indigenous cells of the liver—hepatocytes, endothelium and cholangiocytes—are potential sources for benign and malignant neoplasms as well as nodular, non-neoplastic lesions such as nodular regenerative hyperplasia (NRH) and focal nodular hyperplasia (FNH). Among the benign lesions discussed and illustrated in this chapter are haemangioma, hepatocellular adenoma, focal nodular hyperplasia, nodular regenerative hyperplasia, bile-duct adenoma and angiomyolipoma. Immunohistochemistry plays an important role in distinguishing among subtypes of hepatocellular adenoma and also differentiating adenoma from focal nodular hyperplasia (chiefly by identifying the ‘map-like’ geographic staining pattern of glutamine synthetase in focal nodular hyperplasia). Genotype–histologic phenotype correlations are now well known for four subtypes of hepatocellular adenoma, including the steatotic, atypical, inflammatory and ‘unclassified’ types. The microscopic patterns of hepatocellular carcinoma are diverse, and microtrabecular, acinar (pseudoglandular), fibrolamellar, scirrhous and steatohepatitic variants are all discussed and illustrated. Their specific genomic mutations are also tabulated, including one of the more recently identified and highly specific gene fusion mutations of DNAJB1-PRKACA in fibrolamellar carcinoma (resulting in hyperactivation of protein kinase A). A diagrammatic, algorithmic approach to the selection of special stains and immunostains for the diagnosis of hepatocellular carcinoma versus cholangiocarcinoma is provided. The differing spectrum of paediatric liver tumours is described and illustrated, including hepatoblastoma and calcifying nested epithelial stromal tumour.