LAUSR

A 19-year-old Malay male presented with 1-month history of lower limb swelling, on a background of a 10-year history of PsV. A health screen a year ago noted normal renal function and urinalysis. He denied any preceding infections. On admission, he was hypertensive (BP 158/89) and edematous. Serum creatinine (sCr) was elevated at 363umol/L and urine microscopy revealed glomerular hematuria (> 900 dysmorphic red blood cells per high-power field and urine protein-to-creatinine ratio (uPCR) 7.41 g/g. Serum albumin was 26 g/L. Complements C3 and C4 levels were normal. Hepatitis B, C and HIV serologies were negative. Autoimmune screen was significant for positive ANA (titre ≥ 640; nucleolar pattern) and anti-Streptolysin O antibodies (400 IU/mL), while anti-dsDNA, anti-myeloperoxidase, anti-proteinase 3 and anti-glomerular basement membrane antibodies were negative. Serum and urine electrophoresis and immunofixation were negative for monoclonal gammopathy. Ultrasound demonstrated normal-sized kidneys. Kidney biopsy was performed. Light microscopy showed diffuse mesangial and endocapillary hypercellularity with lobular accentuation of capillary tufts and capillary wall duplication, accompanied by cellular crescents (18/28 glomeruli) and segmental fibrinoid necrosis. Immunofluorescence microscopy showed dominant glomerular staining for IgA, lambda, and C3 mainly involving capillary walls and segmental staining in mesangial regions. Staining intensities for IgG, IgM, C1q, C4, and kappa were negative to trace. Electron microscopy showed electron-dense deposits in subendothelial, mesangial, paramesangial and subepithelial regions. There were no hump-like deposits. Deposits were granular on higher magnification and lacked an organized substructure (Fig. 1). No extraglomerular immune deposits were found. Blood cultures and extensive imaging excluded a concurrent infection. Induction therapy consisted of pulsed methylprednisolone followed by oral prednisolone, and intravenous cyclophosphamide. He received maintenance mycophenolate mofetil, while prednisolone was eventually tapered off 5 months. Partial remission with normal renal function (sCr 70 μmol/L; uPCR 1.38 g/g) was achieved by 9 months.