Ask-Upmark

This kidney biopsy is from a 16-year-old boy with a history of chronic reflux nephropathy. Imaging findings showed unilateral segmental cortical scarring. Although regions of the biopsy show intact renal cortex with normal appearing glomeruli and tubules (Fig. 1), well-demarcated adjacent cortical segments are aglomerular and show severe tubular dropout and interstitial fibrosis (Fig. 2). No definite dysplastic features are noted. This pattern of renal injury supports the clinical impression of unilateral segmental renal hypoplasia (Ask-Upmark kidney). Vesicoureteral reflux is thought to be the main cause of injury in an Ask-Upmark kidney. The condition was first described by the Swedish pathologist Eric Ask-Upmark in 1929.