Page 483 - Concise Pathology for Exam Preparation ( PDFDrive )

468 SECTION II Diseases of Organ Systems

Causes:
• Idiopathic
• Granulomatosis with polyangiitis (Wegener granulomatosis)
• Microscopic polyangiitis
Morphology:
• Same as Type I disease
• Uninvolved segments appear normal without proliferation or inflammation
• In contrast to anti-GBM disease, immunofluorescence studies are negative for
immunoglobulins or complement and no deposits are seen on EM

Clinical Features of RPGN:

• Like nephritic syndrome except that oliguria and azotaemia are more pronounced.
• Proteinuria approaches nephrotic range
• Prognosis related to the number of crescents

Q. Define nephrotic syndrome. Describe its pathogenesis. Enumerate
its causes and clinicopathological features.
Ans. Nephrotic syndrome is a syndrome complex having the following components:
• Daily loss of .3.5 g of protein (less in children)
• Hypoalbuminaemia with protein levels ,3 g/dL
• Generalized oedema/anasarca
• Hyperlipidaemia and lipiduria

Pathogenesis (Flowchart 16.2)

Abnormality in glomerular capillary wall

Increased permeability to plasma proteins leading to massive proteinuria
Also renal catabolism of proteins due to renal
dysfunction
Serum albumin levels decreased beyond compensatory capacity of liver

Hypoalbuminaemia and reversed A:G (albumin:globulin) ratio

Loss of colloid oncotic pressure
• ↑ Aldosterone
• Hypovolaemia-enhanced ADH secretion
• Stimulation of sympathetic system
• ↓ Atrial natriuretic factor
Increased sodium and water retention

Accumulation of fluid in interstitial tissue

• Soft and pitting oedema in periorbital and dependent portions
• Pleural and pericardial effusion may be seen
FLOWCHART 16.2. Pathogenesis of manifestations of nephrotic syndrome.

Clinicopathological Manifestations

1. Proteinuria which may be:
• Selective (loss of low molecular proteins, eg, albumin and transferrin)
• Nonselective (high molecular proteins are lost, eg, high molecular weight globulins)

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