Complement-Mediated Thrombotic Microangiopathies With Predominant Renal Involvement in a Patient With Lupus Nephritis.

Complement-mediated thrombotic microangiopathies (cmTMAs) typically present with thrombocytopenia, microangiopathic hemolytic anemia, and microvascular end-organ damage. Due to an overlapping immune-mediated picture, cmTMAs are often observed in patients with systemic lupus erythematosus (SLE) and lupus nephritis (LN). We present a unique case of LN with cmTMAs predominantly involving the kidneys in the absence of persistent thrombocytopenia. A 20-year-old male with SLE experienced an unwitnessed syncopal event at his home, prompting hospitalization. Initial work-up was consistent with an active lupus flare with multisystem involvement. Despite initial treatment with pulse-dose steroids, he deteriorated with worsening renal function and transfusion-dependent anemia. Blood parameters showed evidence of hemolysis, although platelet counts remained stable and within normal limits throughout the admission. Concern for renal involvement and an atypical clinical presentation prompted a renal biopsy, which revealed immune complexes with evidence of thrombotic microangiopathy. Eculizumab and later ravulizumab were employed as part of his ongoing treatment plan, which resulted in rapid resolution of hemolysis followed by gradual renal recovery over eight weeks. Scientific literature supports the use of terminal complement inhibitors in the treatment of cmTMAs. This report adds to the emerging literature on cmTMAs limited to the kidneys and explores the efficacy of C5 complement inhibition in such patients. .