The renal pathology of primary antiphospholipid syndrome: a distinctive form of endothelial injury

Some features of the vascular and glomerular pathology of primary antiphosp holipid syndrome (APS) are well recognized, but we describe novel glomerula r ultrastructural changes that we consider to be pathognomonic of APS. Rena l biopsies from eight patients with APS were examined by light and electron microscopy. All had anti-cardiolipin antibodies, and the clinical presenta tion ranged from fulminant multi-system disease to isolated proteinuria. By light microscopy, the hexamine silver stain showed a combination of glomer ular basement membrane wrinkling and reduplication. By electron microscopy, redundant, wrinkled segments of basement membrane were accompanied by a 'n ew' straighter thin basement membrane adjacent to the endothelium. In two c ases the presence of these antibodies was not suspected clinically, and the re was no clinical history or evidence of a thrombotic microangiopathy. We describe a distinctive glomerular lesion that represents an unexplained for m of endothelial injury in this syndrome.