Page 690 - Textbook of Pathology, 6th Edition

674 leucocytes, and tubular epithelial cell atrophy and MORPHOLOGIC FEATURES. By light microscopy, the
degeneration (Fig. 22.21,B, C). pattern of involvement varies. These include: focal
Besides the lesions of focal and segmental scarring, a proliferative GN, focal segmental glomerulosclerosis,
variant of FSGS, collapsing glomerulopathy, has been membranoproliferative GN, and rarely RPGN.
described in HIV patients. It is segmental or global By electron microscopy, finely granular electron-dense
glomerular collapse of the tuft along with the presence of deposits are seen in the mesangium.
hyperpasia and hypertrophy of podocytes producing a By immunofluorescence microscopy, the diagnosis is
pseudo-crescent and a rapid decline in renal function. firmly established by demonstration of mesangial deposits
By electron microscopy, diffuse loss of foot processes of IgA, with or without IgG, and usually with C3 and
as seen in minimal change disease is evident but, in properdin.
addition, there are electron-dense deposits in the region
of hyalinosis and sclerosis which are believed to be CLINICAL FEATURES. The disease is common in children
immune complexes. and young adults. The clinical picture is usually characterised
by recurrent bouts of haematuria that are often precipitated
By Immunofluorescence microscopy, the deposits in the
lesions are shown to contain IgM and C3. by mucosal infections. Mild proteinuria is usually present
and occasionally nephrotic syndrome may develop.
CLINICAL FEATURES. The condition may affect all ages
including children and has male preponderance. The most Chronic Glomerulonephritis
common presentation is in the form of nephrotic syndrome (Synonym: End-Stage Kidney)
with heavy proteinuria. Haematuria and hypertension tend Chronic GN is the final stage of a variety of glomerular
to occur more frequently than in minimal change disease. diseases which result in irreversible impairment of renal
Evidence of renal failure may be present at the onset. function. The conditions which may progress to chronic GN,
in descending order of frequency, are as under:
IgA Nephropathy i) Rapidly progressive GN (90%)
(Synonyms: Berger’s Disease, IgA GN)
ii) Membranous GN (50%)
IgA nephropathy is emerging as the most common form of iii) Membranoproliferative GN (50%)
glomerulopathy worldwide and its incidence has been rising. iv) Focal segmental glomerulosclerosis (50%)
It is characterised by aggregates of IgA, deposited principally v) IgA nephropathy (40%)
in the mesangium. The condition was first described by vi) Acute post-streptococcal GN (1%).
SECTION III
Berger, a French physician in 1968 (Not to be confused with
Buerger’s disease or thromboangiitis obliterans described by However, about 20% cases of chronic GN are idiopathic
an American pathologist in 1908 and discussed on page 404). without evidence of preceding GN of any type.

ETIOPATHOGENESIS. The etiology of IgA nephropathy MORPHOLOGIC FEATURES. Grossly, the kidneys are
remains unclear: usually small and contracted weighing as low as 50 gm
i) It is idiopathic in most cases. each. The capsule is adherent to the cortex. The cortical
ii) Seen as part of Henoch-Schonlein purpura. surface is generally diffusely granular (Fig. 22.22). On cut
iii) Association with chronic inflammation in various body section, the cortex is narrow and atrophic, while the
systems (e.g. chronic liver disease, inflammatory bowel medulla is unremarkable.
disease, interstitial pneumonitis, leprosy, dermatitis Microscopically, the changes vary greatly depending
Systemic Pathology
herpetiformis, uveitis, ankylosing spondylitis, Sjögren’s upon the underlying glomerular disease. In general, the
syndrome, monoclonal IgA gammopathy). following changes are seen (Fig. 22.23).
Pathogenesis of IgA nephropathy is explained on the basis i) Glomeruli—Glomeruli are reduced in number and
of following mechanisms: most of those present show completely hyalinised tufts,
i) In view of exclusive mesangial deposits of IgA and giving the appearance of acellular, eosinophilic masses
elevated serum levels of IgA and IgA-immune complexes, which are PAS-positive. Evidence of underlying
IgA nephropathy has been considered to arise from glomerular disease may be present.
entrapment of these complexes in the mesangium. ii) Tubules—Many tubules completely disappear and
ii) There is absence of early components of the complement there may be atrophy of tubules close to scarred glomeruli.
but presence of C3 and properdin in the mesangial deposits, Tubular cells show hyaline-droplets, degeneration and
which point towards activation of alternate complement tubular lumina frequently contain eosinophilic,
pathway. homogeneous casts.
iii) Since there is close association between mucosal iii) Interstitium—There is fine and delicate fibrosis of the
infections (e.g. of the respiratory, gastrointestinal or urinary interstitial tissue and varying number of chronic
tract), it is suggested that IgA deposited in the mesangium
inflammatory cells are often seen.
could be due to increased mucosal secretion of IgA. iv) Vessels—Advanced cases which are frequently
iv) HLA-B35 association has been reported in some cases. associated with hypertension show conspicuous arterial
Another possibility is genetically-determined abnormality of and arteriolar sclerosis.
the immune system producing an increase in circulating IgA.