Focal Nodular Hyperplasia : Microscopic

Comments:
Microscopic Features: The hepatocytes of focal nodular hyperplasia (FNH) resemble normal liver parenchyma and are arranged in thin plates (no more than 2 cells thick). Some foci may show wider cell plates (3 to 4 cells thick). The usual cord arrangement in relation to sinusoids, central veins, and the portal tracts is missing. The hepatocytes lack cytologic atypia and may show increased amounts of glycogen, fat, Mallory hyaline, bile, lipofuscin, iron, and copper.

The fibrous septae contain large, thick-walled vessels and lymphocytic infiltrate with occasional neutrophils, eosinophils, plasma cells or histiocytes. The inflammatory cells are more common around bile ductular structures. Granulomas are rare.