Aggressive Disease and Rare Sequelae in a Unique Case of Atypical Hemolytic Uremic Syndrome Secondary to Adult Onset Still's Disease.

Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) which generally presents as a triad of thrombocytopenia, hemolytic anemia and renal failure. We present the case of a 69-year-old woman with ongoing fevers, arthralgias, diffuse rash and pharyngitis for 3 months. Investigation revealed an elevated erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and ferritin; however, autoimmune and infectious studies were unremarkable, raising the suspicion for adult onset Still's disease (AOSD). Before out patient therapy could be initiated, she presented to our emergency room (ER) with a grand mal seizure and persistence of her initial triad of fevers, arthralgias and rash. Evaluation revealed non-immune hemolytic anemia, thrombocytopenia, and abnormal renal function consistent with TMA and the patient was subsequently started on plasmapheresis, hemodialysis and corticosteroid therapy. ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs)-13 activity was 38%, ruling out thrombotic thrombocytopenic purpura (TTP). A kidney biopsy demonstrated glomerular changes of TMA and a diagnosis of secondary aHUS triggered by AOSD was established. The patient was treated with eculizumab and high dose steroids with improvement in her laboratory values, eventually becoming hemodialysis-independent. This case highlights the clinical urgency in the prompt recognition of AOSD, a potent inflammatory disorder, which when co-existing with a complement- dysregulatory defect, can significantly augment TMA disease severity.