Figure 1.

Adapted from Bioulac-Sage et al., [1]. Algorithm for immunohistochemical (IHC) diagnosis of benign hepatocellular nodules: focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA). Glutamine synthetase (GS) is not always mandatory for the diagnosis of *FNH or **HCA in routine practice. IHC is mandatory for HCA subtyping: markers are presented in grey square with their results positive (+) or negative (−) in tumor (T) and nontumoral liver (NT). LFABP: liver fatty acid binding protein; CRP: C-reactive-protein. Final diagnosis of HCA subtypes is: HNF1a inactivated (H-HCA), inflammatory (IHCA), B-catenin activated (B-HCA), B-catenin activated inflammatory (B-IHCA), or unclassified (UHCA). ^a: GS negativity or positivity limited at the periphery and/or around some veins within HCA. ^b: serum amyloid A staining is usually less sensitive and specific than CRP. ^c: aberrant B-catenin nuclear staining. ^#: needs molecular biology confirmation. ^d: can be difficult to differentiate from FNH.