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Juvenile Slow Progressive Antineutrophil Cytoplasmic Antibody‐Associated Vasculitis Diagnosed After Kidney Transplantation: A Case Report

Dear Editor, A recent report by Dehua et al. described a patient with antineutrophil cytoplasm antibody (ANCA)associated vasculitis (AAV) who was treated with double-filtration plasmapheresis (DFPP, (1)). We report a juvenile case of slow progressive AAV, which developed into end-stage renal disease within 11 years and then recurred soon after kidney transplantation. A 14-year-old female patient developed hematuria and mild proteinuria. Renal biopsy, performed 3 years later, revealed global or segmental sclerosis in 1/3 of her glomeruli. She was diagnosed with focal segmental glomerulosclerosis (FSGS). Urinary protein increased to 1.0 g/day and rituximab and cyclophosphamide were initiated, although serum creatinine (Cr) levels continued to increase. At the age of 25 years, the patient had a rapid increase in serum Cr levels to 11.27 mg/dL and was started on hemodialysis. After 3 months of hemodialysis, she received an ABO-compatible kidney from her father by transplantation. Induction immunosuppression comprised basiliximab and rituximab, while maintenance immunosuppression included tacrolimus, mycophenolate mofetil (MMF), and methylprednisolone.The patient also underwent two sessions of preoperative DFPP to prevent recurrence of FSGS. On postoperative day 15, her serum Cr levels increased to 2.5 mg/dL, and hematuria and urinary protein were detected; methylprednisolone highdose steroid therapy (500 mg/day) was administered for 2 days after performing an allograft biopsy. Light microscopy (Fig. 1) revealed ruptures in the glomerular basement membrane, and there was inflammatory cell infiltration into the glomerular capillaries accompanying approximately 1/3 of glomeruli containing cellular crescents. These pathological findings strongly indicated active vasculitis and the myeloperoxidase (MPO)– ANCA titer increased to 112 U/mL before the surgery and 24.3 U/mL prior to therapy. A clinical diagnosis of recurrent AAV was confirmed, and the primary disease was reassessed and diagnosed as AAV. The patient was then treated with six sessions of DFPP, (exchange volume: 3900 mL per treatment), and four 3-day courses of methylprednisolone therapy (500 mg). Her ANCA titer turned to negative and renal function improved with serum Cr levels of 1.6 mg/dL. Thereafter, the course of the disease improved. In our case, disease onset was characterized by asymptomatic hematuria and mild proteinuria in a young patient, which developed to ESRD within 11 years.This clinical course suggests the diagnosis of an atypical case of AAV, with atypical pathological features progressing eventually. On reassessment, the FSGS lesions of the primary biopsy findings were the scars of vasculitis caused by AAV.