Minimal Change Disease

Overview
  • Minimal Change Disease is a unique etiopathogenic entity which primarily manifests as nephrotic syndrome. It is most importantly characterized by a near lack of observable changes in the glomerulus under light microscopy. However, detailed electron microscopic analysis reveals subtle derangement of podocytes.
Morphology
  • Light Microscopy
    • Characteristically, minimal change disease does not display prominent observable changes of the glomerulus. Cells of the proximal tubule are often filled with lipids but this is probably secondary to resorption of lipoproteins which are normally not filtered by a healthy glomerulus (This is why this disease was originally called "Lipoid Nephrosis").
  • Immunofluorescence
    • No deposition of immune complexes
  • Electron Microscopy
    • Electron Microscopy demonstrates diffuse effacement of the podocyte foot processes. Podocyte are still present but they no longer invest the glomerular basement membrane with clean foot processes.
Etiology
  • The pathogenesis of Minimal Change Disease is still at a speculative stage. Because the disease responds to corticosteroids and is often associated with pediatric allergies, an autoimmune etiology is suspected. Whatever the initial insult, effacement of podocyte foot processes is thought to render the glomerular barrier leaky, reducing glomerular filtration selectivity, and thus precipitating the subsequent pathogenesis of nephrotic syndrome.
Clinical Consequences
  • Classically presents as nephrotic syndrome (i.e. Proteinuria, hypoalbuminemia, generalized edema, hyperlipidemia, and hypercholesterolemia). Albumin appears to be the principle plasma protein lost in the urine and thus is sometimes termed a "Selective Proteinuria".
Epidemiology
  • Minimal Change Disease is the most common cause of nephrotic syndrome in children and rarely occurs in adults. Increased risk in those with possession of HLA-DR7 allele.
Treatment
  • Minimal change disease is highly responsive to corticosteroids and with treatment displays a good prognosis.