Renal pathology 1

Renal pathology 1
Glomerular diseases
Glomerular diseases constitute one of the major problems in nephrology.
They are divided to:
Primary glomerular diseases: in which, the kidney is the only or predominant organ involved.
Secondary glomerular diseases: in which the glomeruli injured secondary to several systemic diseases such as systemic immunological diseases (systemic lupus erythematosus), vascular disorders (hypertension), metabolic diseases (diabetes mellitus), and some hereditary conditions such as Fabry disease.
Glomerular Diseases
PRIMARY GLOMERULOPATHIES
Rapidly progressive (crescentic) glomerulonephritis
Membranous glomerulopathy
Minimal-change disease
Focal segmental glomerulosclerosis
Membranoproliferative glomerulonephritis
IgA nephropathy
Chronic glomerulonephritis

SYSTEMIC DISEASES WITH GLOMERULAR INVOLVEMENT
Systemic lupus erythematosus
Diabetes mellitus
Amyloidosis
Goodpasture syndrome
Microscopic polyarteritis/polyangiitis
Wegener granulomatosis
Henoch-Sch?nlein purpura
Bacterial endocarditis

HEREDITARY DISORDERS
Alport syndrome
Thin basement membrane disease
Fabry disease






Clinical manifestations
The clinical manifestations of glomerular disease are clustered into the five major glomerular syndromes.
Both the primary glomerulopathies and secondary glomerulopathies can result in these syndromes.

The Glomerular Syndromes
Syndrome Manifestations
Nephritic syndrome Hematuria, azotemia, variable proteinuria, oliguria, edema, and hypertension
Rapidly progressive glomerulonephritis Acute nephritis, proteinuria, and acute renal failure
Nephrotic syndrome >3.5 gm/day proteinuria, hypoalbuminemia, hyperlipidemia, lipiduria
Chronic renal failure Azotemia ? uremia progressing for months to years
Isolated urinary abnormalities Glomerular hematuria and/or subnephrotic proteinuria









Microscopical changes of glomerular diseases
The glomerulopathies are characterized by one or more of the following basic microscopical features.
1- Hypercellularity.
The hypercellularity is result from one or more combinations of the following:
• Cellular proliferation of mesangial or endothelial cells.
• Leukocytic infiltration.
• Formation of crescents.
Crescents are composed of proliferating parietal epithelial cells and infiltrating leukocytes.
Fibrin, which leaks into the urinary space, through ruptured basement membranes, is the molecule that elicits the crescentic response.


2- Basement membrane thickening.
By light microscopy, this change appears as thickening of the capillary walls
By electron microscopy such thickening takes one of two forms:
• Deposition of immune complexes, on the endothelial or epithelial side of the basement membrane or within the membrane itself.
• Thickening of the basement membrane due to increased synthesis of its protein components, as occurs in diabetic glomerulosclerosis.
3- Hyalinosis and sclerosis.
Hyalinosis, accumulation of material called hyaline which is homogeneous and eosinophilic extracellular material. Hyaline is made up of plasma proteins that have escaped from the circulation into glomerular structures. Hyalinosis is usually a consequence of endothelial or capillary wall injury and typically the end result of various forms of glomerular damage.
Sclerosis is characterized by accumulations of extracellular collagenous material, either in the mesangial areas as is often the case in diabetic glomerulosclerosis, or involving the capillary loops, or both.

Because many of the primary glomerulopathies are of unknown cause, they are often classified by their histology.
The histologic changes can be further subdivided according to their distribution into:

According to distribution:
Diffuse: involving all glomeruli;
Global: involving the entire glomerulus;
Focal: involving only a proportion of the glomeruli;
Segmental: affecting a part of each glomerulus;


Other subdivision according to distribution:
Capillary loop: affecting predominantly capillary loop
Mesangial: affecting predominantly mesangial regions.