IgA nephropathy and Henoch-Schonlein purpura

Know the pathogenesis of IgA nephropathy

• Unknown

• Thought to be result of mesangial immune deposits (IgA) which represent the Ab component of an immune complex of nonrenal Ag

• Similar lesions develop in liver with increased portal pressure

Know the Light Microscopy, Immuno Fluorescence, and Electron Microscopy findings in IgA nephropathy

• Light Microscopy

• Focal segmental mesangial proliferative glomerulonephritis
• Crescents are small and rarely involve >30% of glomeruli

• ImmunoFluorescence

  • Mostly IgA deposits with some c3 and IgG sometimes present

  • C1q and C4 occasionally seen

• Electron Microscopy

• Electron dense deposits in mesangium
• Subendothelial and subepithelial deposites sometimes seen and indicate more severe disease

Know the clinical presentation and prognosis of IgA nephropathy

• ~35% show macroscopic hematuria occurring with or immediately following URI (50%), or other infection

• Lasts 2-6 days followed by persistent microscopic hematuria

• Dysuria

• Loin pain

• ~35% have asymptomatic proteinuria, microscopic hematuria, and HTN

• ~30% show a variety of symptomatic complexes including:

  • Acute nephritis

  • Nephrotic syndrome

  • Acute / Chronic renal failure

  • Malignant HTN

What are the differences between IgA nephropathy and Henoch-Schonlein purpura?

• HSP is a systemic disease (necrotizing vasculitis)

• Involve purpura on lower extremities

• Arthralgia of large joints

• GI involvement with colic and bleeding

• Renal involvement (IgA nephropathy)

• Somewhat greater severity than IgA nephropathy

What are the clinical and pathologic indicators of progressive disease in Henoch-Schonlein purpura?

• Acute nephritic syndrome

• Nephrotic syndrome

• Crescents

• Subepithelial or subendothelial deposits on EM

Category: Pathology Notes