Severe renal haemosiderosis in a patient with untreated paroxysmal nocturnal haemoglobinuria: a case report

Background: Paroxysmal nocturnal haemoglobinuria (PNH) is a life-threatening disease in which intravascular haemolysis of the red blood cells frequently manifests with chronic haemolysis, anaemia and thrombosis. Renal injury in PNH is associated with chronic haemosiderosis and/or microvascular thrombosis. Herein, we describe a case of haemolytic crisis and severe renal haemosiderosis in a patient who was previously treated for aplastic anaemia (AA) and later developed a symptomatic PNH clone. Case presentation: A 74-year-old woman with acquired AA treated with immunosuppressive therapy 8 years ago was admitted to our hospital with severe haemolytic anaemia and acute kidney injury in the setting of Escherichia coli sepsis. Peripheral blood flow cytometry demonstrated expansion of the small PNH clone detected at diagnosis with clone size now exceeding 80%. Renal biopsy showed extensive brown pigment deposition in most of the proximal tubules and accompanying severe acute tubular injury. The pigment deposits were confirmed to be haemosiderin on Perls’ Prussian blue stain. Based on these biopsy findings and clinical presentation, she was diagnosed with acute tubular injury secondary to Escherichia coli sepsis on a background of chronic kidney disease in part due to chronic intravascular haemolysis associated with untreated PNH. During her admission, she was also found to have large vessel vasculitis and was commenced on high-dose steroids. Her acute haemolysis stabilised after treatment of her sepsis and her renal function also improved. A C5 complement inhibitor was commenced following discharge from hospital. Conclusion: Our case illustrates the potentially severe renal complications of acute on chronic intravascular haemolysis associated with untreated, clinical PNH arising from a history of treated AA. Close monitoring and early intervention of patients with symptomatic PNH is therefore critical.