June 15, 2017
This kidney biopsy from a 41-year-old male with CKD is remarkable for the enlarged and pleomorphic tubular nuclei with focal intra-nuclear clearing. These findings are characteristic of karyomegalic nephropathy. Karyomegalic nephropathy is a rare etiology of progressive renal failure typically presenting in the third decade of life that has been linked to mutations in FAN1, a gene involved in DNA damage repair.1 Karyomegaly is not limited to the kidneys and has been described in other organs including brain, thyroid, lung, esophagus, arteries, among others.2
1. Zhou W, Otto EA, Cluckey A, et al. FAN1 mutations cause karyomegalic interstitial nephritis, linking chronic kidney failure to defective DNA damage repair. Nat Genet 2012; 44: 910-915.
2. Monga G, Banfi G, Salvadore M, et al. Karyomegalic interstitial nephritis: report of 3 new cases and review of the literature. Clin Nephrol 2006; 65: 349-355.