An Unusual Case of Diffuse Alveolar Hemorrhage as a Clinical Manifestation of Atypical Hemolytic Uremic Syndrome: A Case Report.

Hemolytic uremic syndrome (HUS) is a constellation of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury. HUS is subcategorized into primary or secondary HUS. Primary HUS is synonymous with atypical HUS (aHUS) and is attributed to genetic complement deficiency. Diffuse alveolar hemorrhage (DAH) is a serious condition complicating multiple systemic conditions. aHUS presenting as DAH is exceedingly rare. In this case, we present a 75-year-old male patient who presented with generalized weakness, malaise, and hemoptysis. He was found to have hemolytic anemia and thrombocytopenia, with elevated creatinine. Bronchoscopy confirmed DAH. He was started on plasmapheresis with a suboptimal response. aHUS was suspected and the patient was started on eculizumab with subsequent laboratory and clinical improvement. HUS and aHUS can present as DAH. It is very important to recognize both conditions as both are life threatening with high morbidity and mortality.