Renal-Limited Antiphospholipid Syndrome: No-Less-than-Catastrophic

Introduction: Antiphospholipid syndrome (APS) is clinically defined by recurrent vascular thrombosis or pregnancy morbidity and the presence of at least one antiphospholipid antibody (aPL). On rare occasions renal limited disease can lead to acute kidney injury. We herein describe a case of a 26-year-old female with acute renal failure secondary to APS-mediated complete cortical necrosis, whose diagnostic journey began with an elevated partial thromboplastic time (PTT). Case Description: A 26-year-old female with no medical history presented with vomiting and diarrhea caused by adenovirus. She had a prior pregnancy with near-full-term delivery. On admission, her creatinine was elevated at 10 mg/dL, and her urine protein/creatinine ratio was 14 g/day. Her PTT was prolonged at 75s and she tested positive for aPL. Other work up, including ANA, was negative. Peripheral blood smear did not reveal schistocytes, and her complement levels and atypical hemolytic uremic syndrome panel were normal. Renal biopsy (Figure 1) showed diffuse cortical necrosis and marked TMA with extensive fibrin thrombi involving all arterioles, arteries, and glomeruli. She required long-term hemodialysis and was initiated on Warfarin with follow up with hematology. Repeat antibody testing at 6 months was negative. Discussion: This case illustrates that intrarenal TMA can be the initial presentation of primary APS. Morphological abnormalities of TMA alone are not sufficient for a diagnosis and necessitate further investigations. In this patient's case, the biopsy findings, prolonged PTT, and positive aPL favor a diagnosis of APS nephropathy. There have been some case reports of adenovirus associated with transient aPL and thrombosis. However, the clinical significance of this remains unknown. No consensus exists on treating renal limited APS beyond standard anticoagulant therapy for APS. A deeper understanding of the pathogenic mechanisms in APS nephropathy may lead to targeted therapies.