Severe Class III Lupus Nephritis With Concurrent Thrombotic Microangiopathy and Suspected Atypical Hemolytic Uremic...

Systemic lupus erythematosus (SLE) is frequently complicated by lupus nephritis (LN), but the coexistence of thrombotic microangiopathy (TMA) represents a rare and severe manifestation associated with poor renal outcomes. Differentiating between SLE-associated TMA and primary complement-mediated atypical hemolytic uremic syndrome is diagnostically challenging but critical, as it dictates the use of targeted therapies such as terminal complement inhibitors. A 36-year-old female with SLE, lost to follow-up for two years, presented with fatigue, seizures, and anuric renal failure. Laboratory studies revealed severe bicytopenia, metabolic acidosis, and hemolysis with normal ADAMTS13 activity. A renal biopsy confirmed International Society of Nephrology/Renal Pathology Society Class III LN with prominent superimposed TMA. Despite intensive management with high-dose steroids, plasma exchange, and hemodialysis, the patient's refractory state necessitated the initiation of eculizumab. The clinical course was further complicated by a positive direct anti-globulin test (C3 positive/IgG negative), requiring intravenous immunoglobulin for a suspected secondary immune-mediated anemia. This case illustrates the diagnostic complexity of LN-TMA and the therapeutic necessity of a multidisciplinary approach. It underscores the importance of early renal biopsy and the timely utilization of complement inhibition in refractory cases to mitigate irreversible renal damage.