Ask-Upmark Kidney: A Report of 2 Cases

Ask-Upmark Kidney or Renal segmental hypoplasia is a rare congenital kidney disorder associated with hypertension. It was first described by Eric Ask-Upmark in 1929 as congenital unilateral renal hypoplasia. This is a report of 2 cases detected over a 5 year period. The first case is of an 11 month old female who presented with repeated haematuria. Investigations revealed a small, non-functioning right kidney, right vesicouretric reflux, grade 2 and hypertension. A right nephrectomy was indicated. Histopathology revealed renal dysplasia (subtotal/ hypoplastic) with associated uretric atresia. The renal parenchyma showed features of reflux nephropathy. The second case was a post-mortem finding in a 51 year old female who died after a road traffic accident. The lower lobe of the left kidney appeared hypoplastic and segmented with dilated calyces at the hilum, the ureter was dilated. Microscopy showed evidence of early segmental hypoplasia with patchy acute tubular necrosis. Patients usually come to attention due to either hypertension or recurrent urinary tract infections. The condition is more frequent in females and usually unilateral. The kidney is characterised by capsular grooves and fewer pyramids. The hypoplastic areas lack glomeruli and possess thyroid like tubules and thick walled arteries. The reported cases showed similar findings. The pathogenesis is controversial, attributed to vesicoureteric reflux with intrarenal reflux or localised developmental arrest. The scarring could be due to reflux of infected urine or the Tamm-Horsfall protein. Hypertension is attributed to abnormal renin secretion and a nephrectomy usually normalises the blood pressure.