What are the histologic features of acute poststreptococcal glomerulonephritis (APSGN) observed by light microscopy?

Updated: Dec 05, 2018
  • Author: Rajendra Bhimma, MBChB, MD, PhD, DCH (SA), FCP(Paeds)(SA), MMed(Natal); Chief Editor: Craig B Langman, MD  more...
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Answer

As observed by light microscopy, glomerular changes are generalized and diffuse. The glomerular tufts usually appear enlarged and swollen, often filling the Bowman space, and a moderate to marked increase in proliferation of mesangial and epithelial cells is present.

Polymorphonuclear leukocytes are also often observed as part of the inflammatory process, and monocytes may also be present. In persons with the most severe disease, the glomeruli appear bloodless because of the associated edema of the capillary walls, which impedes glomerular perfusion. The increased cell mass expands the central lobular area in a centrifugal pattern, leading to narrowing of the capillary lumens. When the inflammatory process is extensive, the epithelial cells of Bowman capsule proliferate, forming crescents. Few, if any, tubular changes are noted.

Granular deposits of immunoglobulin (Ig) G and C3 along the capillary walls are typically found when the specimen is studied by immunofluorescent microscopy early in the course of the disease; other immunoglobulins (eg, IgM), complement components (eg, C4), properdin, and fibrinogen are often observed.

Later in the course of the disease, the immunoreactants are observed primarily in the mesangium. In the nonstreptococcal forms of postinfectious glomerulonephritis, no significant deposition of complement components is present, although either IgG or IgM may be observed (as may IgA in persons with Henoch-Schönlein purpura or IgA nephropathy).


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