Rapidly Progressive Glomerulonephritis in Catastrophic Antiphospholipid Syndrome: A Diagnostic and Therapeutic Challenge

Introduction: Rapidly progressive glomerular nephritis (RPGN) in catastrophic antiphospholipid syndrome (CAPS) poses significant diagnostic and management challenges. CAPS occurs in ~1% of patients with antiphospholipid syndrome (APS) and has a mortality rate of ~50%. We present a case of a 63-year-old female with APS who presented with AKI. Case Description: A 63-year-old female with past medical history of APS, thrombocytopenia due to ITP, seizure disorder and congenital aortic insufficiency presented with abdominal pain and was found to have AKI with creatinine of 2.5 from baseline 1, and worsening thrombocytopenia (Platelet count of 11,000/μL). Other notable labs on admission include urinalysis RBC 11-50, WBC < 5, protein 30mg/dL; urine microscopy showed RBC casts; serology including ANA, dsDNA, PR3, MPO, anti-GBM were negative; C4 low at 8, C3 normal at 72; infectious workup including blood cultures, hepatitis panel, HIV were negative. She was initially started on pulse dose steroids and IVIG, plasmapheresis and rituximab. Hospital course complicated by anuric renal failure leading to flash pulmonary edema requiring CRRT initiation. Given lack of improvement and dialysis dependence was started on eculizumab. Following this, she was briefly on 2 times a week dialysis but returned to three times a week due to inadequate volume management. She had a 10-week hospital stay during which she developed multiple complications related to her CAPS, including NSTEMI with new reduction in ejection fraction, worsening toxic-metabolic encephalopathy, recurrent strokes with multiple punctate infarcts on brain imaging. She subsequently passed away due to an episode of ventricular tachycardia. She remained dialysis dependent throughout her course. Discussion: RPGN in CAPS is difficult to diagnose due to the bleeding risk associated with kidney biopsy. Given the rarity of CAPS and high mortality, management is often empiric with use of plasmapheresis and immunosuppression. Complement inhibitors, such as eculizumab can be used to treat thrombotic microangiopathy in CAPS and rituximab has been used in CAPS associated with lupus. In our patient, due to uncertainty and severity of renal dysfunction, a multimodal therapy plan with steroids, rituximab and eculizumab was used. Early detection and therapy are important given the high mortality of CAPS.