A case of acute poststreptococcal glomerulonephritis complicated by interstitial nephritis related to streptococcal pyrogenic exotoxin B.

Nobuhiro Kanazawa, Masayuki Iyoda, Junichi Hayashi, Kazuho Honda, Takashi Oda, Hirokazu Honda

Pathology international 2022 Mar

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This paper presents the case of a patient who developed acute kidney injury and nephrotic syndrome following streptococcal cutaneous infection. He presented with microhematuria, severe proteinuria and systemic edema 5 days after infection. Blood examination showed elevated creatinine level, hypocomplementemia, and elevated anti-streptolysin O level. Renal biopsy revealed endocapillary proliferative glomerulonephritis with tubulointerstitial nephritis (TIN). Immunofluorescence revealed C3-dominant glomerular staining, while electron microscopy showed hump-shaped subepithelial deposits. The patient was therefore diagnosed with poststreptococcal glomerulonephritis. The unique histological feature was C3 deposition in the tubular basement membrane (TBM), in which we detected streptococcal pyrogenic exotoxin B (SpeB), a nephritogenic antigen produced by streptococci. No nephritis-associated plasmin receptor or plasmin activity was evident in the TBM. These nephritogenic antigens and upregulation of plasmin activity were observed in glomeruli. This case suggests that TIN after poststreptococcal infection might be partially attributable to SpeB toxicity. © 2022 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.

Citation

Nobuhiro Kanazawa, Masayuki Iyoda, Junichi Hayashi, Kazuho Honda, Takashi Oda, Hirokazu Honda. A case of acute poststreptococcal glomerulonephritis complicated by interstitial nephritis related to streptococcal pyrogenic exotoxin B. Pathology international. 2022 Mar;72(3):200-206