AKI in SLE is typically caused by immune complex-mediated lupus nephritis (LN). However, TMA is a distinct and severe driver of acute renal damage. Histological studies of over 2,300 SLE biopsies show that isolated renal TMA without any immune deposits (no concurrent LN) is exceptionally rare (0.9%). We report a case of a 30-year-old woman with SLE-associated renal-limited TMA, a phenotype even more unique due to the complete absence of systemic markers of microangiopathic hemolytic anemia (MAHA)

The patient presented with facial rash, refractory edema, AKI, and the initial lab tests together fixed with LN – SLE. Her creatinine peaked at 540 µmol/L, necessitating intermittent hemodialysis. Unfortunately, her clinical course was complicated by Streptococcus agalactiae sepsis and CMV pneumonia, which delayed aggressive immunosuppression for more than 2 weeks to treat these infections with Ampicillin and Ganciclovir. Renal biopsy demonstrated microvascular erythrocyte stasis and diffuse tubular vacuolar degeneration, suggesting TMA, but immunofluorescence was negative for all immune deposits, ruling out LN. Notably, she lacked systemic MAHA; schistocytes were absent, and LDH, indirect bilirubin, and haptoglobin were normal. ADAMTS13 activity was 31%, APS and aHUS screenings were negative, and all other etiologies of TMA were excluded, identifying the diagnosis as SLE-associated, renal-limited TMA. Following infection stabilization, PEX and pulse-dose corticosteroids (500 mg/day for 3 days) were initiated

Her renal function began to recover. The serum creatinine on the final day of hospitalization is 243 µmol/L, trending downward after 4 days of no hemodialysis. The patient was discharged after 1 month of admission with a maintenance regimen of Methylprednisolone (32 mg/day), MMF (1.5 g/day), HCQ, and oral Valganciclovir. Follow-up laboratory tests two weeks post-discharge showed a continued improvement in serum creatinine to 102 µmol/L

This case highlights that renal-limited TMA can occur independently of LN and systemic hemolysis. Because systemic markers are often absent, early renal biopsy remains the gold standard for diagnosis. Successful management in this complicated case depends on meticulously balancing infection control with aggressive immunosuppression.