Hepatic amyloidosis in Japan: histological and morphometric analysis based on amyloid proteins

To investigate the relationship between the tissue distribution and the types of amyloid proteins, the detailed histopathologic features of the available liver in 284 cases of amyloidosis were examined. We classified hepatic amyloidosis into three types, namely, the vascular pattern, parenchymal pattern, and stromal pattern according to the topographic distribution pattern of amyloid. Of the 152 amyloid A (AA) cases, all but one exhibited the vascular pattern; the single exception had the parenchymal pattern. Among 117 amyloid light chain (AL) cases, 51.3% exhibited the vascular pattern and 43.6% the parenchymal pattern. The stromal pattern was observed in 5.1% of the cases but was found only in AL amyloidosis. The parenchymal and stromal patterns in the liver seemed to be characteristic morphological distributions of AL amyloidosis. Routine histochemical study is useful to distinguish AL from AA, although some ethnic differences were apparent. Morphometric results showed that the walls of the hepatic arteries with amyloid deposition were significantly thicker than walls in arteries from the control group. The arterial walls in AA amyloidosis, especially, were significantly thicker than walls in AL amyloidosis of any pattern.