A diffuse drop-out signal on chemical shift sequence and a slight arterial enhancement is very suggestive of a steatotic HCA corresponding to the HNF1 subgroup, but the presence of a marked steatosis is not specific to this aetiology and can also be recognised in inflammatory or atypical (corresponding to the -catenin mutated group) HCAs. The gene discussed is HNF1A; the disease is hepatocellular adenoma.