Dihydroxyadenine crystal-induced nephropathy presenting with rapidly progressive renal failure

Abstract

Adenine phosphoribosyltransferase enzyme deficiency is a rare, autosomal recessive disorder. It is a disease limited to the renal system and usually presents with urolithiasis. Herein, we report a young female with dihydroxyadenine (DHA) crystal-induced nephropathy presenting with rapidly progressive renal failure. DHA crystals can be easily diagnosed by their pathognomic color and shape in urine and biopsy specimens. A high index of clinical suspicion helps in the early diagnosis of this potentially treatable renal disease.

Keywords: Adenine phosphoribosyltransferase; Crystal nephropathy; Dihydroxyadenine crystals.

Figure 1. Renal biopsy findings

(A) Marked tubular atrophy, interstitial inflammation, and fibrosis are shown. Higher magnification shows 2,8-dihydroxyadenine (DHA) crystals within the tubular lumens (B) with giant cell reaction in the interstitium and also in the vascular lumen (C). (D, E) The crystals are argyrophilic with silver methenamine and bluish green on Masson’s trichrome stain. (F) The crystals are seen within a tubular lumen under polarized light microscopy.

Figure 2. Urine examination (×40)

(A) The typical brown dihydroxyadenine crystals have a dark outline and central spicules in conventional light microscopy. (B) The crystals appear yellow under polarized light microscopy.

Figure 3. Mechanisms of adenine phosphoribosyltransferase (APRT) deficiency

Adenine cannot be converted to adenosine and is thus oxidized to 2,8 dihydroxyadenine (DHA) by xanthine dehydrogenase (XDH) via an 8-hydroxy intermediate. AMP, adenosine monophosphate.