A Rare Case of Concomitant Thrombotic Thrombocytopenic Purpura with Class V/IV Lupus Nephritis

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a rare disorder marked by microangiopathic hemolytic anemia, thrombocytopenia, low ADAMTS13 activity, and ischemic injury from platelet-rich thrombi. Systemic lupus erythematosus (SLE), a chronic autoimmune disease, can have overlapping features with TTP, though the co-occurrence of lupus nephritis (LN) with TTP is extremely rare. Case Description: A 48-year-old male with HTN presented with syncope, mild hemoptysis, and 3 weeks of lower extremity edema. Labs showed platelets 4,000/µL, Hgb 10 g/dL, haptoglobin <20, LDH >900, schistocytes on smear, albumin 2.2 g/dL, and AKI (Scr 1.95 mg/dL from 0.76). Given a PLASMIC score of 6, he was treated with 5 sessions of plasma exchange (PLEX) and corticosteroids (1 mg/kg/day), with improvement in platelets and hemolysis markers. ADAMTS13 activity was <5%, confirming TTP. Once platelets recovered >100,000/µL, he was biopsied for AKI, proteinuria 14.8 g/g, microscopic hematuria, (+) ANA, (+) SSA/SSB antibodies, and low complements. Kidney biopsy revealed membranous glomerulonephritis with membranoproliferative features consistent with LN class V + IV (mild activity, minimal chronicity), without fibrin thrombi. He was started on MMF, leading to resolution of AKI (Scr 0.75 mg/dL), reduced proteinuria (0.5 g/g), and improved serum albumin (3.4 g/dL). Discussion: SLE is associated with acquired TTP (through mechanism of ADAMTS13 autoantibodies) and with complement-mediated thrombotic microangiopathy (TMA), particularly in pediatric cases. Distinguishing between SLE-associated TMA vs SLE concomitant TTP can be challenging without ADAMTS13 level and biopsy. In a small cohort of 8 patients with SLE and TTP, all patients had TMA lesions and 7/8 had class IV LN on biopsy. Our patient presented in adulthood with nephrotic syndrome, class V LN, and with no TMA lesions cited on biopsy—possibly due to early PLEX therapy. While most cases present with SLE prior to TTP, our patient’s initial presentation was TTP. As active SLE can mimic TMA, distinguishing SLE flares from concomitant TTP is difficult. Clinicians should maintain a high index of suspicion for TTP in SLE/LN patients with anemia and thrombocytopenia. The mortality rate of SLE-associated TTP is higher than that of idiopathic TTP (34-62.5 %), underscoring the importance of early diagnosis and combined immunosuppression with PLEX for optimal outcomes.