Renal morphological changes in idiopathic acute fatty liver of pregnancy

Renal morphological changes are described in four cases of idiopathic acute fatty liver of pregnancy. Light microscopy showed mild glomerular hypercellularity together with thickening and narrowing of capillary loops. In two cases the tubules showed lipid accumulation which included free fatty acids. Electron microscopy showed mesangial cell interposition between the basal lamina and endothelial cells. Glomeruli contained electron dense material in a subendothelial location. Immunoperoxidase stains showed diffuse segmental deposits of fibrin/fibrinogen and IgM in relation to glomerular capillary loops. IgG and C3 were found in three and two cases respectively. Pathogenetic mechanisms including disseminated intravascular coagulation, immune complex deposition and alterations in lipid metabolism are discussed. Coexistent preeclampsia is considered to be an unlikely explanation for the changes. There is a possibility that these renal changes comprise an early feature of idiopathic acute fatty liver of pregnancy.