One Pattern, Many Paths: Secondary FSGS in the Context of Takayasu Vasculitis with Acute Ischemic Stroke

Introduction: Focal Segmental Glomerulosclerosis (FSGS) is a histopathologic pattern of glomerular injury characterized by segmental sclerosis and podocyte effacement on renal biopsy. It may occur as a primary disorder or secondarily in association with a variety of systemic conditions. In this presentation, we discuss a rare case involving a young female who presented with acute ischemic stroke and was found to have subnephrotic-range proteinuria and acute kidney injury. Case Description: A 29-year-old Hispanic female with no history of kidney disease, admitted for hypertensive emergency and acute ischemic stroke. Imaging revealed a large left MCA infarct and multifocal intracranial arterial stenoses. Additional vascular imaging showed segmental narrowing of the thoracic and abdominal aorta, raising suspicion for large-vessel vasculitis. Nephrology was consulted for newly elevated creatinine (~1.5 mg/dL) and subnephrotic range proteinuria (>300 mg/dL) without hematuria. Renal ultrasound was unremarkable. Renal biopsy was performed given the unclear etiology and multiple differentials including vasculitis, thrombotic microangiopathy (TMA), or hypertensive nephrosclerosis. Biopsy revealed FSGS with podocyte effacement and no evidence of immune complex deposition, vasculitis or thrombotic features, these findings are consistent with secondary, likely hypertensive FSGS. Discussion: In this case, proteinuria was ultimately attributed to secondary FSGS. Biopsy was pursued for diagnostic and prognostic purposes, with additional concern for excluding TMA. The patient was later diagnosed with Takayasu arteritis, a systemic large-vessel vasculitis that had previously gone unrecognized. Unfortunately, her first clinical manifestation was ischemic stroke. While secondary FSGS is associated with various conditions, including obesity and smoking, its occurrence in the setting of Takayasu arteritis has not, to our knowledge, been previously described.