Renal Biopsy in Paroxysmal Nocturnal Hemoglobinuria: An Insight into the Spectrum of Morphologic Changes.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, potentially life-threatening disease of blood, characterized by complement-induced intravascular hemolytic anemia and thrombosis. PNH can sometimes present directly with renal manifestations, without showing any hematological manifestation. It, therefore, becomes essential for clinicians and pathologists to be aware of the spectrum of renal changes in PNH. The aim of this study was to document the morphologic changes observed in renal biopsies in patients with PNH. This is an observational study. We report three cases that presented with acute or chronic renal insufficiency and were suspected as PNH on viewing their renal biopsy in light of their clinical and laboratory details. All the three cases were confirmed as PNH on the basis of flow cytometric analysis of CD55 and CD59. Renal biopsy in these patients showed a variety of morphologic changes, however the most consistent finding was moderate-to-heavy siderosis in their kidneys. PNH per se may be difficult to diagnose clinically and sometimes present directly with renal manifestations. It is, therefore, prudent for nephrologists and nephropathologists to be aware of the spectrum of renal changes in PNH.