Renal cortical siderosis: imaging findings and clinical relevance

Renal cortical hemosiderosis is the accumulation of iron in the renal cortex. On MRI, this can be inferred by marked cortical T2 hypointensity and loss of signal on in-phase imaging relative to opposed-phase imaging. Although classically associated with paroxysmal nocturnal hemoglobinuria, renal hemosiderosis can be seen in a variety of pathologic conditions associated with acute or chronic renal injury. We present a case of a 59-year-old female that developed acute kidney injury while hospitalized for management of hydronephrosis and hepatic abscess with imaging features on MR angiography and renal parenchymal biopsy consistent with renal cortical hemosiderosis. Combined with other laboratory results, this finding supports the diagnosis of atypical hemolytic uremic syndrome, a condition with poor prognosis for which timely treatment is essential. Thus, recognition of renal cortical hemosiderosis on imaging may facilitate appropriate clinical workup and timely management.