Acute tubulointerstitial nephritis with germinal centers in antineutrophil cytoplasmic antibody-associated vasculitis: A case report and literature review

Abstract

Rationale:Occasionally, tubulointerstitial lesions can be found in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, significantly isolated tubulointerstitial nephritis (TIN) with germinal centers is rare.Patient concerns:A 17-year-old Chinese Han patient showed rapidly progressive glomerulonephritis, anuria, and serum creatinine of 19.4mg/dL.Diagnosis:He had positive ANCA targeting myeloperoxidase (55.0RU/mL). The renal biopsy showed crescent formation in 100% of glomeruli. Of special note, the glomerular crescents were surrounded by granulomatous inflammation, extensive tubular destruction or disappearance, and massive interstitial infiltration. A diagnosis of AAV was thus made with the involved organ restricted to the kidney.Interventions:The patient underwent 7 rounds of plasmapheresis, 3 pulses of methylprednisolone therapy (500mg per pulse), and oral prednisolone (50mg/d). Rituximab (500mg) was used after the plasma exchange treatment.Outcomes:ANCA was negative, while anti-modified C-reactive protein (anti-mCRP) antibodies remained positive. The patient was dependent on hemodialysis. We found anti-mCRP antibody in the serum of the patient, with the major epitope on amino acids 35 to 47 of mCRP.Lessons:We proposed that the anti-mCRP antibody might play an important role in this case of acute TIN in AAV.