Clinical significance and long-term evolution of minimal change histopathologic variants and of IGM nephropathy among Egyptians. 
In children, the most frequent idiopathic nephrotic syndrome is minimal change nephrotic syndrome (MCNS).  Typically, MCNS shows no abnormalities by light microscopy: "nil disease".  Beside this classic picture, there are other minor light microscopic abnormalities which are considered as MCNS variants.  Our 172 MCNS patients were divided into a nil disease group, two groups of MCNS variants (mild mesangial hypercellularity and mild mesangial thickening) and a fourth group with normal light microscopy and diffuse IgM deposition (IgM nephropathy group).  The relation of this fourth group to MCNS is controversial in the literature.  Age and serum creatinine were significantly different in the four histologic groups (P=0.03 for age and 0.047 for serum creatinine).  Comparing the groups in pairs, it appeared that these significant differences were due to significantly higher age and serum creatinine in the mild mesangial hypercellularity group than in the IgM nephropathy group (P = 0.02 for age and 0.01 for serum creatinine).  The groups were similar as regards follow-up creatinine clearance and early and late steroid response.  We concluded that mild mesangial hypercellularity may differ from other MCNS forms as regards age at presentation and renal function.  We also suggest that IgM nephropathy with normal light microscopy is similar to MCNS.