Multiple spontaneous liver cell adenomas of different types (liver adenomatosis)

In 1999, Nguyen et al divided focal nodular hyperplasia (FNH) in 2 groups, the classical and nonclassical. The former also included those cases of FNH with classical characteristics exhibited "on a subtle scale," whereas the latter included among others mainly the telangiectatic FNH (T-FNH) variant. Hepatocellular adenoma (HCA) was classically considered by definition a neoplasm with no ductal or ductular differentiation, but today the spectrum of HCA does include variant 3, which may have CK7+ ductules. Owing to genotypic-phenotypic correlation, T-FNH (synonymous with progressive FNH of others) is not considered yet as part of the spectrum of FNH, instead it is diagnosed as a variant of HCA, which now includes 4 variants. Variant-3, which may contain CK7+ ductules, and is also termed HCA with ductal/ductular differentiation, corresponds to T-FNH. Notwithstanding the nosologic advancement, and outside the "archetypal" types, the differential morphologic diagnosis of spontaneous HCA versus FNH may remain problematic as ductular proliferation in some cases of FNH may be scanty and hard to find. In some histologic overlapping cases of FNH and HCA the morphologic diagnosis may be very difficult or even impossible (especially in small lesions) and molecular biology may be of critical assistance. A prototypical case of surgically resected multiple spontaneous liver cell adenomas of various types, including HCA of T-FNH type and steatotic type, previously interpreted in different ways, affecting a young girl, is presented herein.