Abstract: SA-PO0688
Thrombotic Microangiopathy in Anti-Antimelanoma Differentiation-Associated Gene 5 Antibody (MDA5) Dermatomyositis: An Unusual Kidney Complication
Session Information
- Glomerular Diseases: Complement-Mediated Glomerulopathies and Infection-Related GN
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Alahmadi, Ziad, Johns Hopkins University, Baltimore, Maryland, United States
- Nguyen, Alison, Johns Hopkins University, Baltimore, Maryland, United States
- Koirala, Abbal, Johns Hopkins University, Baltimore, Maryland, United States
Introduction
Anti-MDA5 dermatomyositis is a rare inflammatory myopathy characterized by cutaneous ulceration, interstitial lung disease, and systemic inflammation driven by interferon overactivation. Renal involvement, particularly thrombotic microangiopathy (TMA) is extremely rare complication.
Case Description
A 55 year old man with progressive anti-MDA5 dermatomyositis manifesting as ulcerative skin disease with digital necrosis, arthritis, myositis, ILD with pneumothorax, and myocarditis complicated by pericardial tamponade. The patient developed an acute kidney injury with creatinine rising from baseline 1.1 mg/dL to 4.39 mg/dL with disproportionate urine protein to creatinine ratio of 3.52 (to which was initially presumed to be Acute tubular injury), with thrombocytopenia and markers of active hemolysis. Kidney biopsy revealed chronic TMA with focal active glomerular fibrin thrombi, membranoproliferative glomerulonephritis pattern with negative immunofluorescence and tubuloreticular inclusions on electron microscopy all consistent with interferon-mediated endothelial injury. Workup showed elevated sC5b-9, normal ADAMTS13, and no pathogenic complement gene variants on genetic testing. Tacrolimus was discontinued for possible drug-associated TMA contribution. Treatment for anti-MDA5 dermatomyositis included pulsed steroids, IVIG, and cyclophosphamide. Eculizumab 900mg weekly was initiated for TMA with improvement in platelets, hemolysis markers, and creatinine stabilization at 3.30 mg/dL. Our plan is to initiate tofacitinib, which works via JAK-STAT pathway to reduce type I interferon signaling, which plays a pivotal role in driving disease progression in anti-MDA5 dermatomyositis.
Discussion
This case illustrates TMA as a serious renal complication of anti-MDA5 dermatomyositis, likely driven by interferon-mediated endothelial activation rather than primary complement dysregulation that showed clinical improvement with Eculizumab. Tubuloreticular inclusions support this mechanism. This highlights the importance of kidney biopsy in distinguishing TMA etiologies and the potential role for complement blockade as bridging therapy to primary disease control.