October 16, 2017
Diagnose This! (October 16, 2017)
What is your diagnosis?
The photomicrograph shows a distended tubule with an intratubular crystalline cast with argyrophilia. While crystalline casts can be seen from calcium phosphate, calcium oxalate and others, the presence of argyrophilia on silver stain is characteristic for 2,8-Dihydroxyadenuria (DHA) crystals. 2,8-DHA is a rare, autosomal recessive trait caused by a genetic deficiency in adenine phosphoribosyltransferase (APRT). Accurate diagnosis is critical (especially in those with limited chronicity) as treatment exists that can ameliorate renal damage in some patients. And, in patients with the undiagnosed disease who undergo a transplant, the disease will reoccur unless pharmacologic intervention is initiated. Of note, argyrophilic, birefringent crystals can also be seen in patients exposed to triamterene which should always be excluded before a diagnosis of 2,8-DHA is rendered.