Fig. 1

Kidney biopsy images from initial presentation (a – 40x, b – 10x PAS), 2 weeks later (c – 40x Jones, d – 10x PAS, e – EM 8000x) and 2 months later (f – 40x, g – 10x PAS). At initial presentation, glomeruli have patent capillary loops with few hypertrophic vacuolated podocytes (a - arrow). There is acute tubular injury and clusters of microcystically dilated tubules containing proteinaceous casts (b - arrow). Two weeks later, glomeruli show more pronounced collapsing features with prominent vacuolated podocytes and capillary obliteration (c - arrow). Microcystically dilated tubules remain with acute tubular injury and an increase in tubulointerstitial scarring (d). Electron microscopy demonstrates extensive foot process effacement (e) without electron dense deposits or tubuloreticular inclusions. Two months after initial presentation, advanced glomerular collapse and sclerosis are present with persistent focal and segmental epithelial cell hypertrophy and hyperplasia (f - arrow), and dilated tubules with progressive tubulointerstitial scarring (g)