Fig. 1.

Progressive TMA changes over subsequent renal transplant biopsies. A A relatively ‘bloodless‘ glomerulus containing small hilar thrombi in the first biopsy. B Second biopsy with the glomerulus (long arrow) showing segmental thrombosis and subtle erythrocyte fragmentation. An arteriole cut longitudinally (short arrow) shows endothelial cell swelling and intimal expansion by myxoid/fibrinoid-necrotic material. C Second biopsy with the arteriole (long arrow) showing luminal obliteration by fibro-myxoid intimal thickening and erythrocyte extravasation and fragmentation. The arteriole (short arrow) shows a swollen endothelium and marked myxoid subendothelial thickening, compromising the lumen. D Third biopsy showing chronic TMA changes in the form of a ‘glomeruloid body‘ (arrow) produced by proliferating endothelial cells, myocytes and myofibroblasts within an arteriole/small interlobular artery in response to injury, and prominent ischaemic glomerular and tubulointerstitial changes.