[Clinical pathology of the glomerulus--from phenomenon to entity. The minimal glomerular lesion].

: There are several clinical conditions which can induce minor glomerular lesions. Clinical symptoms range from severe proteinuria with nephrotic syndrome to slight hematuria with or without proteinuria. There are two principal morphological conditions associated with minor glomerular lesions: 1. The initial stage of glomerulopathies. 2. Stable minor glomerular lesions, which have not changed their appearances for years. Ad 1.: Regarding severe proteinuria, there are two possible causative conditions: membranous glomerulonephritis stage I (according to EHRENREICH and CHURG), or the initial stage of amyloidosis. Recurrent hematuria may result from hereditary nephropathy of Alport's syndrome. Ad 2.: Non-evolving minor glomerular lesions with symptomes of severe proteinuria can be defined as so-called minimal change nephropathy. Under certain conditions, morphology of minor glomerular lesions can result from focal and segmental sclerosis. Concerning hematuria, minimal glomerulonephritis (diagnosed by immunofluorescence) and benign familial hematuria (diagnosed by electron microscopy) must be differentiated. The two above-mentioned conditions are discussed in terms of the triple diagnostic procedures of light microscopy, immunofluorescence and electron microscopy. For diagnosing minor glomerular lesions, it is recommended to use frozen sections instead of paraffin embedded, which can give false negative results.