Page 684 - Textbook of Pathology, 6th Edition

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Figure 22.14 RPGN (post-infectious type), light microscopic appearance. There are crescents in Bowman’s space forming adhesions between
the glomerular tuft and Bowman’s capsule. The tuft shows hypercellularity and leucocytic infiltration.

mentally induced if the lungs are previously injured by viral cells and leucocytic infiltration. Fibrin thrombi are
or bacterial infection or exposed to hydrocarbons. The frequently present in the glomerular tufts.
Goodpasture’s antigen appears to be a component of collagen ii) Tubules—Tubular epithelial cells may show hyaline
type IV.
droplets. Tubular lumina may contain casts, red blood
Type II RPGN: Immune complex disease. A small propor- cells and fibrin.
tion of cases of post-streptococcal GN, particularly in adults iii) Interstitium—The interstitium is oedematous and
and sometimes of non-streptococcal origin, develop RPGN. may show early fibrosis. Inflammatory cells, usually
The evidences in support of post-infectious RPGN having lymphocytes and plasma cells, are commonly distributed
SECTION III
immune complex pathogenesis are granular deposits of in the interstitial tissue.
immune complexes of IgG and C3 along the glomerular iv) Vessels—Arteries and arterioles may show no change,
capillary walls, lowering of blood complement levels and but cases associated with hypertension usually show
demonstration of circulating complexes. severe vascular changes.
Type III RPGN: Pauci-immune GN. These include cases of Electron microscopic findings vary according to the type
Wegener’s granulomatosis and microscopic polyarteritis of RPGN. Post-infectious RPGN cases show electron-dense
nodosa. The pathogenesis of pauci-immune GN is yet not subepithelial granular deposits similar to those seen in
fully defined. However, majority of these patients are ANCA- acute GN, while cases of RPGN in Goodpasture’s
positive, implying a defect in humoral immunity. Serum syndrome show characteristic linear deposits along the
complement levels are normal and anti-GBM antibody is GBM (Fig. 22.15).
negative. There is little or no glomerular immune deposit
Systemic Pathology
(i.e. pauci-immune). Immunofluorescence microscopy shows following
patterns in various types of RPGN:
MORPHOLOGIC FEATURES. Grossly, the kidneys are linear pattern of RPGN in Goodpasture’s syndrome
usually enlarged and pale with smooth outer surface (large (type I RPGN), containing IgG accompanied by C3 along
white kidney). Cut surface shows pale cortex and congested the capillaries.
medulla. Granular pattern of post-infectious RPGN (type II
Light Microscopic findings vary according to the cause RPGN) consisting of IgG and C3 along the capillary wall.
but in general following features are present (Fig. 22.14): Scanty or no deposits of immunoglobulin and C3 in
pauci-immune GN (type III RPGN).
i) Glomeruli—Irrespective of the underlying etiology,
all forms of RPGN show pathognomonic ‘crescents’ on the CLINICAL FEATURES. Generally, the features of post-
inside of Bowman’s capsules. These are collections of pale- infectious RPGN are similar to those of acute GN, presenting
staining polygonal cells which commonly tend to be as acute renal failure. The patients of Goodpasture’s
elongated. Eventually, crescents obliterate the Bowman’s syndrome may present as acute renal failure and/or
space and compress the glomerular tuft. Fibrin deposition associated intrapulmonary haemorrhage producing
is invariably present alongside crescents. Besides the recurrent haemoptysis. Prognosis of all forms of RPGN is
crescents, glomerular tufts may show increased cellularity poor. However, post-infectious cases have somewhat better
as a result of proliferation of endothelial and mesangial outcome and may show recovery.