Nephritis-Associated Plasmin Receptor-Positive Post-Streptococcal Acute Glomerulonephritis Showing Full-House Pattern: A Case Report

Introduction: Post-streptococcal acute glomerulonephritis (PSAGN) is a disease in which patients develop hematuria and leg edema following streptococcal infection, which may lead to acute nephritic syndrome and nephrotic syndrome. We present a case involving acute kidney injury and nephrotic syndrome with nonspecific pathological findings for PSAGN, which posed diagnostic challenges. Case presentation: A 25-year-old man presented with leg edema, cough, nephrotic syndrome, severe kidney dysfunction, and hematuria. Blood tests showed elevated antistreptolysin O levels and decreased complement C3 levels; therefore, PSAGN was suspected. Light microscopy revealed membranoproliferative glomerulonephritis, immunofluorescence staining revealed a full-house pattern, and electron microscopy revealed subendothelial deposition. The diagnosis was difficult, however, positive glomerular staining for nephritis-associated plasmin receptor and plasmin activity strongly suggested an infection-related etiology of glomerulonephritis. Treatment included the administration of 500 mg of methylprednisolone for 3 days, followed by 4 weeks of treatment with 50 mg of prednisolone. Subsequently, the dosage was reduced to 40 mg, and the patient was discharged. Urinary findings revealed resolution of hematuria 1 year after discharge. Conclusion: When PSAGN is suspected and other diseases are difficult to exclude, nephritis-associated plasmin receptor staining should be considered.