Nephronophthisis by Light Microscopy

Nephronophthisis is an autosomal recessive tubulointerstitial nephropathy that is a leading genetic etiology of end-stage renal disease in children and young adults. Approximately 60% of patients with a known genetic etiology of nephronophthisis are due to homozygous deletion of the NPHP1 gene. The histopathologic lesions associated with nephronophthisis are shown in these photomicrographs. (A) A tubular floret profile with complicated tubular branching in at least 4 directions (PAS; original magnification ×400). (B) Macula densa-like lesions (arrows) are tubular profiles in which there is a transition to a grouping of cells with crowded, hyperchromatic nuclei and a high nuclear: cytoplasmic ratio (H&E; original magnification ×400). (C) A tubular diverticulum (arrow) with perpendicular outpouching of the tubular cytoplasm and associated overlying TBM thinning (PAS; original magnification ×600).  (D) Periglomerular fibrosis with PAS-positive thickening surrounding Bowman’s capsule of an intact glomerulus (PAS; original magnification ×400).

Reference: CP Larsen, SM Bonsib, ML Beggs, JD Wilson. Fluorescence in situ hybridization for the diagnosis of NPHP1 deletion-related nephronophthisis on renal biopsy. 2018. Hum Path. [epub ahead of print]