Immune Complex Glomerulonephritis: A Rare Presentation in Systemic Sclerosis.

abstractSystemic sclerosis (SSc) and renal involvement most frequently present as scleroderma renal crisis (SRC). Immune complex-mediated glomerulonephritis (GN) is an exceptionally rare renal manifestation in SSc and may complicate timely diagnosis and management. We report the case of a 40-year-old woman with a history of hypertension and Raynaud's phenomenon who presented with progressive dyspnea, bilateral lower limb edema, and oliguria. Laboratory investigations demonstrated rapidly deteriorating renal function (serum urea/creatinine - 71/6.44 mg/dL rising to 82/7.35 mg/dL within 24 h), nephrotic-range proteinuria (urine protein-creatinine ratio ≈ 11.6), hematuria (25-30 red blood cells/high-power field), and borderline low complement C3 (80.3 mg/dL). Autoimmune analysis revealed a speckled antinuclear antibody pattern (1:100) with Scl-70 positivity. Ultrasound showed enlarged kidneys with increased cortical echogenicity, and two-dimensional echocardiography confirmed moderate pulmonary arterial hypertension. Renal biopsy demonstrated diffuse proliferative GN with neutrophilic exudation, immunoglobulin G (IgG) and C3 immune complex deposition on immunofluorescence, and acute tubular injury, without thrombotic microangiopathy, thereby excluding SRC. The patient underwent hemodialysis and was initiated on low-dose corticosteroids. She was lost to follow-up after discharge. This case underscores an atypical and rare renal presentation of SSc, emphasizing the necessity of considering alternative diagnoses when renal dysfunction occurs without features of SRC. Early renal biopsy is essential to guide appropriate and individualized therapy in such cases.