Clinical and histologic resolution of poststreptococcal glomerulonephritis with large subendothelial deposits and kidney failure.

A 16-year-old male adolescent who had fallen and scratched his knee developed cold-like symptoms. Gross hematuria, oliguria, and peripheral edema appeared about 2 weeks after his fall. Tests showed hypocomplementemia, increased antistreptolysin O titers, and severe kidney failure with hematuria/proteinuria. Kidney biopsy showed endocapillary proliferative glomerulonephritis visible using light microscopy and deposits of complement C3 on capillary walls, detectable using immunofluorescence microscopy. Although these findings suggested that he had acute poststreptococcal glomerulonephritis (APSGN), electron microscopy failed to detect subepithelial humps, a feature typical of APSGN; instead, massive electron-dense deposits were visible in the subendothelial space. A second biopsy performed 3 months later showed mesangial cell proliferation without endocapillary proliferation using light microscopy and the disappearance of subendothelial electron-dense deposits in electron micrographs, suggesting that APSGN had resolved. Glomerular deposition of nephritis-associated plasmin receptor, a nephritogenic streptococcal antigen, was observed in the first biopsy specimen, but not the second. The patient required 4 hemodialysis treatments, and within 1 year of supportive therapy only, kidney function and urinalysis had normalized. This is an interesting case of APSGN presenting with acute kidney injury and atypical massive subendothelial deposits, but no subepithelial deposits on electron microscopy, a pattern resembling that in membranoproliferative glomerulonephritis type I.