minimal change glomerulopathy

Definition: Minimal change disease (MCD) is the commonest cause of nephrotic syndrome in childhood.

Its exact prevalence in renal biopsy specimens is depending on the local policies for renal biopsy in nephrotic syndrome.

Clinical synopsis

 More common in boys (2 : 1 M : F)
 Average age at presentation: 3 years
 Nephrotic syndrome is main feature
 microscopic hematuria (10–30%)
 hypertension (20%)
 Acute renal failure is a rare complication.

• usually due to acute tubular necrosis presumed due to altered hemodynamics and hypovolemia

Laboratory

 Rarely associated with reduced renal function at presentation.
 Serum complement levels normal
 Selective proteinuria, predominantly albumin

Microscopical synopsis

 normal glomeruli

• Glomeruli show no morphological abnormalities on routine light microscopy.
• No significant abnormalities on light microscopy and normal glomerular capillary walls.

 thin and delicate glomerular basement membrane
 normal mesangial cellularity
 or very mild mesangial hypercellularity described

• more common in those with hematuria
• may be associated with poorer initial response to therapy and more frequent relapses

 normal mesangial matrix
 no interstitial fibrosis
 no segmental sclerosis
 Tubules show hyaline droplet change
 Interstitium and blood vessels normal

Immunofluorescence

 No deposition of immunoglobulins or complement components

Ultrastructure

 Podocyte foot process effacement on electron microscopy
 glomerular basement membrane

• normal thickness
• without deposits

 visceral epithelial cells

• fused foot processes
• diffuse effacement of foot processes
• microvillous transformation representing the irregular epithelial-cell surface that occurs in proteinuric states

Differential diagnosis

 The possibility of unsampled focal segmental glomerulosclerosis (FSGS) cannot be completely excluded when only a small number of glomeruli (less than 250) are examined.

Main differential diagnoses are:
 IgM nephropathy
 C1q nephropathy
 FSGS
–*ensure that deep cortical glomeruli are present
–* issues of sampling

• FSGS is associated with increased glomerular size

 C1q nephropathy

• Idiopathic glomerulonephritis
• mild mesangial expansion
• mesangial deposition of C1q (in the absence of other diagnoses such as lupus nephritis)
• May morphologically mimic lupus nephritis
• Possible variant of MCN or FSGS
• Presents with steroid resistant/dependent nephrotic syndrome or severe proteinuria
• Outcome dependent on morphological features of either MCN or FSGS

 IgM nephropathy

• Idiopathic glomerulonephritis
• mesangial expansion and hypercellularity
• isolated diffuse mesangial IgM deposits
• Possible variant of MCN or FSGS
• Behavior appears to be MCN-like in the absence of morphological features of FSGS