Page 682 - Textbook of Pathology, 6th Edition

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chiefly polymorphs and sometimes monocytes (acute
exudative lesion). There may be small deposits of fibrin
within the capillary lumina and in the mesangium.
ii) Tubules—Tubular changes are not very striking.
There may be swelling and hyaline droplets in tubular
cells, and tubular lumina may contain red cell casts.
iii) Interstitium—There may be some degree of interstitial
oedema and leucocytic infiltration.
iv) Vessels—Changes in arteries and arterioles are seldom
present in acute GN.
Electron microscopic findings, aside from confirming the
light microscopic findings, demonstrate the characteristic
electron-dense irregular deposits (‘humps’) on the
epithelial side of the GBM. These deposits represent the
immune complexes (Fig. 22.13).
Immunofluorescence microscopy reveals that the irregular
deposits along the GBM consist principally of IgG and
complement C3.

CLINICAL FEATURES. Typically, the patient is a young
child, presenting with acute nephritic syndrome (page 660),
Figure 22.11 Flea-bitten kidney. The kidney is enlarged in size and
weight. The cortex shows tiny petechial haemorrhages visible through having sudden and abrupt onset following an episode of sore
the capsule (arrow). throat or skin infection 1-2 weeks prior to the development
of symptoms. The features include microscopic or
intermittent haematuria, red cell casts, mild non-selective
MORPHOLOGIC FEATURES. Grossly, the kidneys are proteinuria (less than 3 gm per 24 hrs), hypertension,
symmetrically enlarged, weighing one and a half to twice periorbital oedema and variably oliguria. Less often, the
the normal weight. The cortical as well as sectioned surface presentation may be as nephrotic syndrome. In adults, the
show petechial haemorrhages giving the characteristic features are atypical and include sudden hypertension,
SECTION III
appearance of flea-bitten kidney (Fig. 22.11). oedema and azotaemia. Development of hypertension in
Light microscopic findings are as under (Fig. 22.12): either case is a poor prognostic sign.
i) Glomeruli—The glomeruli are affected diffusely. They Prognosis varies with the age of the patient. Children
are enlarged and hypercellular. The diffuse hyper- almost always (95%) recover completely with reversal of
cellularity of the tuft is due to proliferation of mesangial, proliferative glomerular changes. Complications arise more
endothelial and occasionally epithelial cells (acute often in adults and occasionally in children. These include
proliferative lesions) as well as by infiltration of leucocytes, development of rapidly progressive GN, chronic GN,
uraemia and chronic renal failure.

Systemic Pathology

Figure 22.12 Acute post-streptococcal GN, light microscopic appearance. There is increased cellularity due to proliferation of mesangial cells,
endothelial cells and some epithelial cells and infiltration of the tuft by neutrophils and monocytes.