Amyloid-like Fibronectin Deposits in the Liver: A Novel Morphologic Finding

Amyloid deposits in the liver are recognized by their hematoxylin and eosin (H&E) findings, consisting of acellular eosinophilic deposits in various compartments of the liver parenchyma, including the stroma, vessels, and rarely the hepatocytes. H&E findings that suggest amyloid are then confirmed by Congo red stains and subtyped when clinically needed. Two cases are reported with sinusoidal deposits of acellular material that closely mimicked amyloid on H&E, but were Congo red negative. Mass spectrometry-based proteomic analysis identified the material as fibronectin. In 1 case, the deposits were located in the sinusoids of a well-differentiated hepatocellular carcinoma and in 1 case in the sinusoids of a benign liver.