renal glomerular

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I- Overview :

The N.G correspond to inflammatory lesions whose starting point is located in the capillary network of the glomeruli. This individualized reached the morphologically gloméruk "nephritis.

II- PATHOGENESIS glomerulonephritis :

The causes are diverse G.N :

  • immunological mechanisms.
  • metabolic, vascular, thrombotiques, hereditary or unknown.

But the immune phenomena, are the most important and intervene according 2 key terms :

1° – Fixing at the glomerular capillary walls, antigen complex- circulating antibody, related supplement.

2° – Fixing at the glomerular basement membrane antibodies against it.

III- DAMAGE BASIC glomerular :

1- Deposits :

Depending on their nature are distinguished :

  • Non immune deposits (hyalins).
  • The immune deposits. L’immuno fluorescence les classes : in granular deposits (immune complexes) very common, linear deposits (AC anti membrane glomérulaire).

According to their headquarters :

They are in the mesangium :

mesangial deposits or inter capillaries or with respect to the basement membrane (MB), we can then observe :

  • On the external side of the M.B (between podocytes and M.B) : deposit- extra membraneux.
  • Within the M.B : deposits intra membranous.
  • on i<; internal side of M.B (between M.B and endothelial cell) : endomembraneux deposits or under endothelial.

2- Cell proliferation :

The glomerulus contains 3 different types of cells :

  1. The epithelial cell of the parietal layer of Bowman's capsule, the visceral layer : les podocytes.
  2. The c glomerular capillary endothelial Mule.
  3. Mesangial cell or endocapillary.

The proliferating cells : it is mainly mesangial cell and epithelial cell. The proliferation of the latter type is serious : in that case, the cells of the two layers is "rejoignei it" and form a "crescent" that bridges cell urinary space.

3- Topography :

Lesions may interest all or part of the glomeruli. The whole of each glomerulus or the latter sector :

1°- pm compared to all glomeruli :

  • If all glomeruli are affected : G.N diffuse ;
  • If some glomeruli are affected : focal G.N.

2°- I V & rsquo; ir relation to each glomerulus :

  • If all of the glomerulus is hit : overall achievement.
  • If part of the glomerulus is affected : segmental reached.

IV- CLASSIFICATION :

2 groups :

  • apparently primitive GN (pathological classification)
  • secondary GN (etiological classification).

V- Glomerulonephritis APPARENTLY PRIMITIVE :

They are complex, both morphologically and clinical qu'immunopathologique.

A- G.N WITH MINIMAL DAMAGE glomerular :

C & rsquo; is the case of pure nephrotic syndrome and nephrosis child lipoidic. It combines syndrome :

  • Selective massive proteinuria without hematuria.
  • Hypoproteinemia with hypoalbuminemia.
  • Hyperlipidemia and edema.
  • Renal function and BP are normal.
  • In urine, observed many hyaline and granular casts containing lipid droplets refractive : are the refractile bodies.

Microscopically :

  • The glomeruli are substantially normal to the optical microscope.
  • L & rsquo; n & rsquo glomerular; that is visible through the electron microscopy study : it consists of a fusion of the pedicels of podocytes, thus forming a continuous cytoplasmic tongue lining the outer side of the glomerular capillary M.B. No deposit n & rsquo; is visible and immunofluorescence tests are negative.

Evolutionarily :

Before the steroids era, the death was common and usually secondary to infection. The first treatment by steroids, and now by immuno depressants changed the prognosis is good.

B- G.N DIFFUSES :

a- non-proliferative :

It's the extra membranous G.N (gnem) , about 15% primitive G.N .

→ clinically : It is characterized by the insidious onset of proteinuria and nephrotic syndrome.

C & rsquo; esi the most important cause of nephrotic syndrome in adults, it is idiopathic in most cases but reported a large number of antigens involved.

  • Extrinsic antigens of diverse nature :

– infectious : Hepatitis B, filariose, malaria.
– drug or toxic : mercure, or, penicillamine,

  • intrinsic antigens :

– tumor antigen : For G.N extra membranous colic cancer or Hodgkin's disease.
– G.N extra membraneuse du lupus.

→ on the pathological plane :

1° – Optical microscope : diffuse wall thickening of the glomerular capillary MB, related to the existence of deposits on its outer side.

2° – Electron microscope : for deposits on the external side of the MB, situated under the feet of podocytes.

3°- En immuno fluorescence : granular deposits of I g G and C3 along the capillary walls.

→ evolutionarily :

The complete spontaneous remission is the rule, but it is followed by frequent recurrences, leading to kidney failure. Treatment with corticosteroids and anti- inflammatory gives little or no results. The prognosis is unfavorable. We must remove the cause when it's . possiole.

b- Prolifératives :

1° – G.N capillary pure endo (acute G.N) :

Clinique :

  • Usually occurs, A recent streptococcal infection of the upper airways.
  • Injury more common in children than in & rsquo; adult.
  • gross hematuria.
  • Oligurie.
  • Frequently hypertension.
  • In this case there is no nephrotic syndrome.
  • Complement Decrease (C3).
  • Sometimes kidney failure.
  • The piotéinurie is abundant.
  • Renal biopsy (unnecessary in the typical form).

→ In the optical microscope :

at low magnification, she shows :

Glomeruli "big" hyper inflated- cell because there is a proliferation of glomerular cells (especially mesangial cells) and swelling of endothelial cells associated with a tuft of infiltration by polymorphonuclear.

A high magnification :

we sometimes see peui deposits or "humps" ; they sit on the outer side of M.B, are rare, scattered, bulky, triangular, color red or green trichrome.

→ En immuno fluorescence : These deposits contain some of IgG and especially C3 +++ → La M.E : Confirms topography "humpus" between podocytes and M.B

  • Evolution : Usually toward healing or clinical remission.

– For kids : Excellent evolution 90% cases.
– For adults : Good evolution in 50 at 70 % cases.
– Very rarely, adverse developments : deaths during the acute phase (exceptional) uremia infection and cardiovascular complications- vascular.

2° – Glomérulonéphrite membrane- proliferative :

  • Represented 10% of G.N. primitives,
  • clinical Reminder :
  • In 1/3 cases : as acute glomerulonephritis.
  • In other cases : nephrotic syndrome (frequent) with microscopic hematuria, asymptomatic proteinuria.
  • Dam blood serum complement (You C3 +++) and anemia (inconstant).

→ Renal biopsy :

All glomeruli are big, characterized by thickening of the capillary walls and pai a capillary cell proliferation with endo deposits under – endothéliaux (type I) or dense deposits intra membranous (type II).

  • In type I : deposits analysis in immunofluorescence shows immunoglobulins (IG1 and the fraction complement C3.
  • In type II : their analysis by immunofluorescence only shows the fraction complement C3.
  • Evolution : frequently (despite various therapeutic attempts) to the & rsquo; IRC months or years.

3° – Glomerulonephritis endo and extra hair ( 5% primitive GN) :

→ Clinical Reminder :

  • Symptoms depend on the etiology and % croissants.
  • sudden onset, gross hematuria, proteinuria, kidney failure within a few weeks or months.
  • Sometimes nephrotic syndrome occurs during various affections : PAN – Wegener's granulomatosis – Good Pasture's syndrome +++ (GN + pulmonary hemorrhage) – the HSP- bacterial endocarditis- la G.N post streptococcique.

→ Renal biopsy, on observe :

  • a diffuse involvement of all glomeruli.
  • a proliferation of mesangial cells and epithelial cells of Bowman's capsule, which will form proliferating cell growing obliterating Bowman's space.
  • these growing, beginning in cell, become after fibro- cellular and fibrous .
  • There are also tubular atrophy diffuse d & rsquo; variable intensity.

→ In immuno- fluorescence

  • The deposits depend on & rsquo; etiology.
  • Most often in the growing fibrin.
  • Sometimes deposits C3jau level of "humps", IgA deposits (HSP), deposits & rsquo; IgG and C3 linear with anti M.B exceptional glomerular AC (particularly in Good pasture syndrome).

→ Change :

  • Rapid and severe despite treatment (heparin, platelet dispersants) to renal insufficiency 3 at 12 month.
  • Prognosis depends on the etiology, the number of glomeruli with crescents and the growing area.

C- GLOMERULONEPHRITES FOCALES :

a- The focal segmental : is about 10% primitive GN.

→ Clinical Reminder :

  • Hematuria or proteinuria isolated.
  • Often nephrotic syndrome steroid- resistant.

→ Renal biopsy : Focal segmental reached :

  • There are healthy and pathological glomeruli glomeruli.
  • At the latter part of the glomerulus is injured.
  • Lesion : hyaline membrane endo deposits, segmentaires.

→ En immuno fluorescence : deposits of IgM or C3.

→ Change : Despite corticosteroid treatment (corticorésistance, the disease progresses to IRC.

b- Glomerulonephritis focal segmental must be distinguished :

→ The G.N focal segmental itself :

The lesions are similar to cells described in G.N endo and extra hair, but they are Focal and segmental :

  • focus : healthy glomeruli alternate with pathologic glomeruli.
  • Segmentaires : at each glomerulus, mesangial proliferation interested in a glomerulus sector, it is accompanied by a proliferation extra- capillaries (croissants).
  • En immuno fluorescence : deposits are diffuse, variable and depend on the etiology, same causes as for G.N endo and extra hair, especially :

– The bread.
– The HSP.
– Bacterial endocarditis.

  • clinically : same symptoms that also G.N endo and extra hair but less "noisy".
  • The evolution : is quick enough to kidney failure .

→ Berger's disease or mesangial deposits G.N IgA :

Very frequented, about 20% primitive G.N, which defines : mesangial deposits of IgA, So the immunofluorescence is required to make the diagnosis. These deposits are diffuse.

  • clinically :

– recurrent hematuria +.+ (macroscopic or microscopic)
– sometimes proteinuria.
– Rarely an infection site.
– Sometimes elevated serum IgA.

  • renal biopsy :

– In light microscope :

normal kidney or increased mesangial axes, or focal segmental reached :

  • focus : healthy glomeruli alternate with pathologic glomeruli.
  • segmentaire : moderate mesangial cell proliferation affecting only secteui the glomerulus.

– In immunofluorescence and M.E :

diffuse mesangial deposits of IgA interesting the +++, optionally IgG, C3.

  • Evolution :

– Good in general.
– In 20% cases, evolution to IRC, with hypertension.

D- G.N INCLASSEES :

  • fairly frequent : 10% about primitive GN.
  • This framework includes the advanced too primitive GN or not within a framework defined : deposits, cell proliferation, do not allow the store in the types described above.
Schematic representation of the glomerulus
A : Schematic cross-section of & rsquo; d & rsquo a lobule; a normal glomerulus, observed by optical microscopy. B : Delimitation of areas and extramembraneux endomembraneux.
ondomembraneux deposits. A : schematic. B : Mesangial deposits fibrinoid . C : Deposits in endothelial ► : Trichrome de Masson ; x 1000
extramembraneux deposits. A : schematic representation. B : Dépôts et extramembraneux diffuse réguliers ► : extramembraneuse of glomérulonéphrite. C : scattered deposits bumps or hump:. ► Trichrome de Masson ; x1000

Course of Dr Madoui – Faculty of Constantine