Systemic lupus erythematosus complicated by thrombotic microangiopathy with atypical HUS features: A case report

Rationale: Systemic lupus erythematosus (SLE)-associated thrombotic microangiopathy with features of atypical hemolytic uremic syndrome (aHUS) is a rare but life-threatening complication. Early recognition is challenging because of its overlapping clinical manifestations with other thrombotic microangiopathies. Patient concerns: A 49-year-old man with SLE presented with anemia, thrombocytopenia, and multi-system involvement. Despite initial immunosuppressive therapy, his hematologic parameters progressively deteriorated, with hemoglobin decreasing to 89 g/L and the platelet count to 54 × 10 9 /L. Diagnoses: Laboratory investigations demonstrated elevated lactate dehydrogenase (501 U/L) and markedly increased soluble complement membrane attack complex (sC5b-9, >1790 ng/mL). ADAMTS13 activity was normal (75.41%), excluding thrombotic thrombocytopenic purpura. Based on the clinical and laboratory findings, the patient was diagnosed with SLE-associated aHUS. Interventions: Following the diagnosis, the patient received eculizumab, a monoclonal antibody targeting complement component C5. Outcomes: Within 6 days of eculizumab treatment, hemoglobin increased to 102 g/L, and the platelet count recovered to 108 × 10 9 /L, indicating a rapid hematologic response. Lessons: This case highlights that aHUS can occur as a severe complication of SLE, even in male patients. Complement-mediated thrombotic microangiopathy may coexist with and be triggered by immune hemolysis in SLE. Early recognition and prompt complement inhibition with eculizumab can produce an ultra-rapid hematologic response and may be critical for improving patient outcomes.