Irreversible severe kidney injury and anuria in a 3-month-old girl with atypical haemolytic uraemic syndrome under administration of eculizumab.

Histopathological findings can play an important role in the management of atypical haemolytic uraemic syndrome (aHUS). We report a case of aHUS that did not recover from anuria, despite the administration of eculizumab, with impressive histopathological findings. A 3-month-old girl was admitted because of poor feeding, vomiting, and diarrhoea without haemorrhage. She had anuria and severe hypertension, and laboratory results showed haemolytic anaemia with schizocytes, thrombocytopenia, and renal impairment. Although no mutations in the complement system or diacylglycerol kinase epsilon were detected, she was diagnosed with aHUS owing to the clinical course and by the exclusion of Escherichia coli infection and thrombotic thrombocytopenic purpura. Plasma exchange was performed once at day 2 and eculizumab therapy was started from day 18, with a severe infusion reaction at the first administration. After the initiation of eculizumab, although the serum lactate dehydrogenase level improved gradually, she did not recover from anuria. Pathological findings of the kidney biopsy at day 37 included diffuse arteriolar and arterial luminal stenosis with remarkable thickness and sclerotic changes of the media and intima, which are suggestive of aHUS. In addition, most glomeruli had global sclerosis and were collapsed, and 80% of the tubulointerstitial compartment showed atrophic changes with infiltration of inflammatory cells. The present case is possibly a kidney-specific fulminant type of aHUS. Although showing efficacy against thrombotic microangiopathy, eculizumab did not improve kidney function. The pathological findings reflected the severe and irreversible kidney injury.